1. 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。FreeBSD 的最新稳定版本是 12.1。
2. 艾克斯：
AIX 是 IBM 提供的一系列专有操作系统。 AIX 代表高级交互式执行程序。最初它是为 IBM RT PC RISC 工作站设计的，后来它被用于各种硬件平台，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 网络服务器。它是通过 The Open Group 的 UNIX 03 标准认证的五个商业操作系统之一。 AIX 的第一个版本于 1986 年推出。AIX 的最新稳定版本是 7.2。
AIX 和 FreeBSD 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. |