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. FreeBSD：
FreeBSD 是 FreeBSD 项目提供的免费开源操作系统。它是在两个类 Unix 操作系统 Berkeley Software Distribution (BSD) 和 Research Unix 的基础上设计的。它与 Linux 操作系统非常相似。它是早期著名的操作系统之一，但与其他操作系统相比，现在使用较少。 FreeBSD 的第一个版本于 1993 年推出。
iOS 和 FreeBSD 的区别：
| S.No. | IOS | FREEBSD |
|---|---|---|
| 1. | It was developed and is owned by Apple Incorporation. | It was developed and is owned by The FreeBSD Project. |
| 2. | It was launched in 2007. | It was launched in 1993. |
| 3. | Its target system types are smartphone, music player and tablet computer. | Its target system types are server, workstation, 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 FreeBSD are IA-32, x86-64, ARM, MIPS and PowerPC. |
| 5. | It kernel type is Hybrid. | Its kernel type is Monolithic with modules. |
| 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 is by source or network binary update. |
| 9. | File systems supported by iOS are HFS+ and APFS. | File systems supported by FreeBSD are UFS2, ZFS, ext2, ext3, FAT, ISO 9660, UDF and NFS. |
| 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. |