1. 并行虚拟机(PVM)：
PVM 是一种为异构分布式计算设计的软件工具。该软件于 1989 年在橡树岭国家实验室创建，并于 1991 年在田纳西大学重写。在这个系统中，它允许一个异构网络，该网络可以由被视为单个并行虚拟机的分布式处理器集合组成。它允许可用于单个大型并行计算机的异构 UNIX 和/或 Windows 机器的集合。它使用C/C++、FORTRAN等简单的语言来实现并行计算。
2. 消息传递接口(MPI)：
MPI 是一种消息传递库标准。它是库而不是编程语言，编译器使用该库。它是分布式存储系统编程常用的方法。它用于定义例程。它在分布式内存机器上很有用。它支持 C、C++、FORTRAN 和Java等编程语言。它支持通信模式，即标准、同步、缓冲和就绪。
并行虚拟机 (PVM) 和消息传递接口 (MPI) 之间的区别：
| Sr. No. | Basis | PVM | MPI |
|---|---|---|---|
| 1. | Standard | It is the standard used for heterogeneous distributed computing. | It is the standard used for the message passing. |
| 2. | Concept | It is the concept of virtual machine. | It does not have such kind of abstraction. |
| 3. | Heterogeneity | It supports heterogeneity in the terms of machines, networks, and applications. | It supports heterogeneity in the terms of communication of heterogeneous messages. |
| 4. | Operating system | It is distributed operating system. | It is not a distributed operating system, it is the library for writing application program. |
| 5. | Message support | It supports simple message. | It supports rich message. |
| 6. | Topology | In this no topology is used. | It supports logical communication topology. |
| 7. | Portability | It is portable over performance. | It is portable over flexibility. |
| 8. | Category | It is a programming language. | it is the library which is used by compilers. |
| 9. | Control | It holds it’s control over process and resources. | It is only concerned about the message passing. |
| 10. | Fault Tolerance | It has a strong fault tolerance. | It is more susceptible to faults. |
| 11. | Nature | It is dynamically reconfigurable. | It is a static model. |