1. 视窗：
Windows 是一组由 Microsoft Incorporation 提供的各种专有图形操作系统。它也被称为Microsoft Windows 。它目前包括 Windows NT 和 Windows IoT 作为其家族成员。早些时候，它包括不再使用的 Windows 9x、Windows Mobile 和 Windows Phone。它是个人计算机中最常用的操作系统。微软于 1985 年推出了 Windows 的第一个版本。它具有带有模块的混合内核。
2. OpenVMS：
OpenVMS是由美国数字设备公司(DEC)开发的多用户多处理操作系统。它是一种基于虚拟内存的操作系统，设计用于分时、批处理和事务处理。它可用于许多平台，包括服务器和工作站。它是使用 BLISS、VAX Macro、C、Ada、PL/I、Fortran、UIL、Pascal、SDL、C++ 和 DCL 编写的。 OpenVMS 的第一个版本于 1977 年推出。该操作系统中使用的内核是带有模块的单体。
Windows 和 OpenVMS 的区别：
| S.No. | WINDOWS | OPENVMS |
|---|---|---|
| 1. | It was developed by Microsoft Incorporation. | It was developed by Digital Equipment Corporation (DEC). |
| 2. | It was launched in 1985. | It was launched in 1977. |
| 3. | Its target systems types are workstation, personal computers, media center, tablets and embedded systems. | Its target system types are server and workstation. |
| 4. | Computer architectures supported by Windows are IA-32, x86-64, IA-64, ARM, Alpha, MIPS and PowerPC. | Computer architectures supported by OpenVMS are VAX, Alpha and IA-64. |
| 5. | Its kernel type is Hybrid with modules. | Its kernel type is Monolithic with modules. |
| 6. | Its native APIs are Win32 and NT API. | Its native APIs are Proprietary. |
| 7. | It has the preferred license Proprietary and Source available. | It has the preferred license of Proprietary. |
| 8. | The non-native APIs supported through its subsystems are DOS API, Win16, POSIX and .NET. | The non-native APIs supported through its subsystems are POSIX. |
| 9. | Its package management is MSI or custom installer. | Its package management is PCSI or VMSINSTAL. |
| 10. | It has default GUI ‘on’. | It does not have default GUI ‘on’. |
| 11. | File systems supported by Windows are NTFS, FAT, ISO 9660, UDF, HFS+, FATX and HFS. | File systems supported by OpenVMS are Files-11, ISO 9660, NFS and CIFS. |