1. 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。FreeBSD的最新稳定版本是12.1。
2. AIX：
AIX是IBM提供的一系列专有操作系统。 AIX代表Advanced Interactive eXecutive。最初，它是为IBM RT PC RISC工作站设计的，后来又用于各种硬件平台，例如IBM RS / 6000系列，基于PowerPC的系统，System-370大型机，PS-2个人计算机和Apple Network Server。它是五个具有The Open Group的UNIX 03标准认证的商业操作系统之一。 AIX的第一个版本于1986年发布。AIX的最新稳定版本是7.2。
AIX和FreeBSD之间的区别：
| AIX | FreeBSD |
|---|---|
| It was developed and is owned by IBM. | It was developed and is owned by The FreeBSD Project. |
| It was launched in 1986. | It was launched in 1993. |
| Current stable version is 7.2. | Current stable version is 12.1 |
| Its target system type is Server, NAS and workstation. | Its target system type is server, workstation, NAS and embedded systems. |
| Computer architectures supported are POWER, PowerPC-AS, PowerPC and Power ISA. | Computer architectures supported are IA-32, x86-64, ARM, MIPS and PowerPC. |
| Kernel type is Monolithic with modules. | Kernel type is Monolithic with modules. |
| Package management is installp and RPM. | Package management is Port collections and packages. |
| The native APIs are SysV/POSIX. | The native APIs are BSD/POSIX. |
| Preferred license is Proprietary. | Preferred license is BSD. |
| File systems supported are JFS, JFS2, ISO 9660, UDF, NFS, SMBFS and GPFS. | File systems supported are UFS2, ZFS, ext2, ext3, FAT, ISO 9660, UDF and NFS. |