1. iOS：
iOS是苹果公司提供的移动操作系统。它主要是为iPhone和iPod Touch等Apple移动设备设计的。它以前被称为iPhone OS。它是基于Darwin(BSD)操作系统的类Unix操作系统。它是仅次于Android的世界第二使用最多的移动操作系统。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年发布。
2. FreeBSD：
FreeBSD是FreeBSD项目提供的一个免费的开源操作系统。它是基于两个类似Unix的操作系统Berkeley Software Distribution(BSD)和Research Unix设计的。它与Linux操作系统非常相似。它是较早的著名操作系统之一，但是现在与其他操作系统相比，它的使用率有所降低。 FreeBSD的第一个版本于1993年发布。
iOS和FreeBSD之间的区别：
| 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. |