Desktop and Mobile Operating Systems: Types, Purposes, and File Compatibility

An operating system (OS) is the software layer that manages a device’s hardware and runs its applications, and every OS falls into a category with a purpose: desktop/workstation systems (Windows, macOS, Linux, ChromeOS) for general computing, and mobile systems (Android, iOS/iPadOS) for phones and tablets. The key differences a technician has to know are who controls each platform, where its apps come from, and — critically — that applications and many file formats do not automatically move between them. A program built for one OS will not run on another, and a proprietary file format usually needs a compatible application on the receiving machine before anyone can open it.

Desktop and workstation operating systems

Microsoft Windows is the dominant business desktop OS. It is closed source, licensed per device, and ships in multiple editions with different feature sets — the differences between them matter enough on the help desk that they get their own article. Windows’ strength is application breadth: the overwhelming majority of commercial desktop software, especially line-of-business and legacy applications, targets Windows first or Windows only.

macOS is Apple’s closed-source desktop OS, and it runs only on Apple hardware — that pairing is a licensing condition, not just a technical one. It is built on a UNIX foundation, which is why its Terminal accepts many of the same commands as Linux. For a technician, the practical points are: Mac software installs commonly arrive as .dmg disk images or .pkg installers, updates and apps flow through System Settings and the App Store, and Windows executables (.exe) will not run on it without virtualization or compatibility layers.

Linux is open source: the source code is publicly available, and anyone can modify and redistribute it. It ships as distributions (Ubuntu, Fedora, Debian, and many others) that bundle the Linux kernel with package managers and desktop environments. In the field you meet Linux mostly on servers, network appliances, and the occasional developer workstation. Support is community-driven or paid-vendor depending on the distribution.

ChromeOS is Google’s browser-centric OS for Chromebooks. It assumes cloud storage and web apps, needs little local maintenance, and is popular in schools and kiosk-style deployments. Its limitation is the flip side of its simplicity: traditional desktop applications don’t install on it, so a user who needs a specific Windows program needs a different machine or a hosted/virtual solution.

Mobile operating systems

Android is Google’s mobile OS, and its defining trait is openness. It is open source (built on the Linux kernel), and Google licenses it to many hardware manufacturers — Samsung, Motorola, OnePlus, and others — each of which customizes the interface and bundles its own apps. That is why two Android phones can look and behave quite differently while running “the same” OS. Apps normally come from the Google Play Store, but Android also permits third-party app stores and direct APK (Android Package) installation, called sideloading. That flexibility is a feature and a support burden: sideloading is a common mobile malware vector, and manufacturer customization means update timing varies by vendor.

iOS (and iPadOS, its tablet variant) is Apple’s closed-source mobile OS, and it runs only on Apple devices. Apps come from the Apple App Store, full stop — there is no sanctioned sideloading path in the standard configuration. Apple controls the hardware, the OS, and the store, which produces consistent behavior across devices and predictable, long update support, at the cost of flexibility.

The contrast between the two is a favorite exam target, so keep the columns straight:

	Android	iOS / iPadOS
Source model	Open source (Linux-based)	Closed source
Hardware	Many manufacturers	Apple devices only
App sources	Google Play, third-party stores, sideloading	Apple App Store only
Customization	Heavy (OEM skins, launchers)	Minimal
Update control	Varies by manufacturer/carrier	Directly from Apple, uniform

File and application compatibility between operating systems

This is the concept that generates real tickets. Two separate compatibility layers exist, and users routinely confuse them:

Applications are compiled for a specific OS. A Windows program is a Windows binary; it will not launch on macOS or Linux, and vice versa. Many major vendors ship separate versions per platform (a macOS build and a Windows build are different products), and plenty of niche or legacy software is Windows-only with no counterpart at all.

Files need a compatible application, not a matching OS. The file itself is just data — the question is whether the receiving computer has software that understands the format. If a user creates a document in a Windows-only application and sends the native file to a Mac user who has no application capable of reading that format, the Mac user simply cannot open it usefully. The file isn’t corrupt, and the email didn’t mangle it; there is no installed program that speaks that format. The fixes are the ones you’d suggest on a real call: export to a universal format (PDF, CSV, plain text), use a cross-platform equivalent application, or use a web/cloud version of the tool — the same reasoning that makes cloud collaboration platforms attractive for mixed-OS teams.

Two related points round this out. Open standard formats (PDF, TXT, CSV, standard image formats) open nearly anywhere, which is why “save as PDF” is the universal peace treaty between platforms. And storage media have their own compatibility layer: a drive formatted NTFS (New Technology File System, the Windows default) is read-only on a stock Mac, while exFAT is the common choice for external drives that must move between Windows and macOS.

Vendor life cycles and end-of-life

Every OS has a support life cycle, and an OS past its end-of-life (EOL) date stops receiving security patches. Running an EOL system is a security risk regardless of how well it still “works,” and it progressively loses application support as developers drop it. On mobile, the same idea appears as devices that can no longer receive OS updates — which eventually blocks app updates too, the exact ceiling behind the compatibility errors covered in iPhone app and OS update issues. When a customer asks why their old device “suddenly” can’t run something, the vendor life cycle is usually the answer.

How the 220-1202 exam tests this

• A statement-selection question about Android or iOS where the wrong options swap their traits — e.g., attributing single-vendor hardware control to Android or sideloading to iOS. Anchor on the table above.
• A scenario where a file created in a platform-specific application is sent to someone on a different OS, asking you to identify the most likely problem. The answer centers on the missing compatible application/format support, not file corruption or email failure.
• A “best OS for this purpose” scenario: cloud-only student laptop (ChromeOS), video editing on Apple hardware (macOS), open-source server (Linux).
• A scenario involving an unsupported or EOL operating system, asking for the primary risk (no more security updates).

OS types are foundation material for the whole Operating Systems domain — the full 220-1202 study guide shows what builds on top of them, and a round of practice questions confirms the traits have stuck.

Quick reference

• Desktop OS types: Windows (closed source, broadest app support), macOS (closed source, Apple hardware only, UNIX-based), Linux (open source, distributions), ChromeOS (browser/cloud-centric).
• Android: open source, Linux-based, many manufacturers, Google Play plus sideloading and third-party stores.
• iOS/iPadOS: closed source, Apple hardware only, App Store only, uniform updates.
• Applications are OS-specific — a Windows binary won’t run on macOS or Linux.
• Opening a file requires a compatible application on the receiving system; the OS alone doesn’t determine it.
• Cross-platform escape hatches: PDF/CSV/plain-text exports, cross-platform apps, cloud/web versions.
• NTFS is read-only on stock macOS; exFAT works for drives shared between Windows and Mac.
• EOL software gets no security patches — that’s the risk, and the reason to upgrade.