1.iOS：
iOS 是由 Apple Incorporation 提供的移动操作系统。它主要是为 iPhone 和 iPod Touch 等苹果移动设备设计的。它早先被称为 iPhone 操作系统。它是一个基于Darwin(BSD) 操作系统的类Unix 操作系统。它是仅次于 Android 的全球第二大移动操作系统。它主要用 C、C++、Objective-C、汇编语言和 Swift 编写。 iOS 的第一个版本于 2007 年推出。
2. DragonFlyBSD :
DragonFly BSD 是由 Matthew Dillon 开发的免费开源操作系统。它是一个类 Unix 操作系统，其设计灵感来自 FreeBSD 操作系统。基本不用于个人电脑。它专为服务器、工作站、NAS 和嵌入式系统而设计。主要使用的编程语言是C语言。 DragonFly BSD 的第一个版本于 2003 年推出。它具有 Hybrid 内核。
iOS 和 DragonFlyBSD 的区别：
| S.No. | IOS | DRAGONFLYBSD |
|---|---|---|
| 1. | It was developed and is owned by Apple Incorporation. | It was developed by Matthew Dillon. |
| 2. | It was launched in 2007. | It was launched in 2003. |
| 3. | Its target system types are smartphone, music player and tablet computer. | Its target system types are workstation, server, NAS and embedded systems. |
| 4. | Computer architectures supported by iOS are ARMv8-A (iOS 7-present), ARMv7-A (iPhone OS 3-iOS 10) and ARMv6 (iPhone OS 1-iOS 4.2.1). | Computer architectures supported by DragonFlyBSD is x86-64. |
| 5. | It does not have package management. | Its package management is dports or pkg. |
| 6. | Its native APIs are Cocoa and BSD-POSIX. | Its native APIs are BSD/POSIX. |
| 7. | It has preferred license is Proprietary, APSL and GNU GPL. | It has preferred license of BSD. |
| 8. | Its update management is Software Update. | Its update management are git, cvsup, rsync and pkg. |
| 9. | File systems supported by iOS are HFS+ and APFS. | File systems supported by DragonFlyBSD are UFS1, MFS, ext2, FAT, HAMMER and ISO 9660. |
| 10. | The non-native APIs are not supported by its subsystems. | The non-native APIs supported by its subsystems are Mono, Java, Win16, Win32 and Linux. |