虽然没有完整 对并行和并发这两个术语的区别达成一致， 许多作者做了以下区分:

在并发计算中，一个程序可以在任意时刻执行多个任务。 在并行计算中，一个程序是多个任务紧密合作的程序 解决一个问题。

所以并行程序是并发的，但是像多任务操作系统这样的程序也是并发的，即使它运行在一台带有 只有一个核心，因为多个任务可以在任何时刻进行。

来源:Peter Pacheco的《并行编程介绍》

在编程中，并发是独立的组合 执行进程，而并行是同时执行 计算的(可能相关的)。 -安德鲁·格兰德

And

Concurrency is the composition of independently executing computations. Concurrency is a way to structure software, particularly as a way to write clean code that interacts well with the real world. It is not parallelism. Concurrency is not parallelism, although it enables parallelism. If you have only one processor, your program can still be concurrent but it cannot be parallel. On the other hand, a well-written concurrent program might run efficiently in parallel on a multiprocessor. That property could be important... - Rob Pike -

为了理解其中的区别，我强烈建议你去看看Rob Pike(Golang的创作者之一)的视频。并发不是并行

虽然没有完整 对并行和并发这两个术语的区别达成一致， 许多作者做了以下区分:

在并发计算中，一个程序可以在任意时刻执行多个任务。 在并行计算中，一个程序是多个任务紧密合作的程序 解决一个问题。

所以并行程序是并发的，但是像多任务操作系统这样的程序也是并发的，即使它运行在一台带有 只有一个核心，因为多个任务可以在任何时刻进行。

来源:Peter Pacheco的《并行编程介绍》

Concurrent programming regards operations that appear to overlap and is primarily concerned with the complexity that arises due to non-deterministic control flow. The quantitative costs associated with concurrent programs are typically both throughput and latency. Concurrent programs are often IO bound but not always, e.g. concurrent garbage collectors are entirely on-CPU. The pedagogical example of a concurrent program is a web crawler. This program initiates requests for web pages and accepts the responses concurrently as the results of the downloads become available, accumulating a set of pages that have already been visited. Control flow is non-deterministic because the responses are not necessarily received in the same order each time the program is run. This characteristic can make it very hard to debug concurrent programs. Some applications are fundamentally concurrent, e.g. web servers must handle client connections concurrently. Erlang, F# asynchronous workflows and Scala's Akka library are perhaps the most promising approaches to highly concurrent programming.

Multicore programming is a special case of parallel programming. Parallel programming concerns operations that are overlapped for the specific goal of improving throughput. The difficulties of concurrent programming are evaded by making control flow deterministic. Typically, programs spawn sets of child tasks that run in parallel and the parent task only continues once every subtask has finished. This makes parallel programs much easier to debug than concurrent programs. The hard part of parallel programming is performance optimization with respect to issues such as granularity and communication. The latter is still an issue in the context of multicores because there is a considerable cost associated with transferring data from one cache to another. Dense matrix-matrix multiply is a pedagogical example of parallel programming and it can be solved efficiently by using Straasen's divide-and-conquer algorithm and attacking the sub-problems in parallel. Cilk is perhaps the most promising approach for high-performance parallel programming on multicores and it has been adopted in both Intel's Threaded Building Blocks and Microsoft's Task Parallel Library (in .NET 4).

我会试着用我自己的方式来解释它，它可能不是计算机术语，但它能给你一个大概的概念。

让我们以家务为例:洗碗，倒垃圾，修剪草坪等，我们有三个人(线程)A, B, C来做这些事情

并发: 三个人独立地开始不同的任务，例如，

A --> cleaning dishes
B --> taking out trash 
C --> mowing the lawn 

在这里，任务的顺序是不确定的，响应取决于工作量

并行: 在这里，如果我们想要提高吞吐量，我们可以分配多个人来完成一项任务，例如，清洁盘子，我们分配两个人，A擦洗盘子，B洗盘子，这可能会提高吞吐量。

洗碗:

A --> soaping the dishes
B --> washing the dishes

等等

希望这能给你一些启发!现在转到其他答案中解释的技术术语;)

将原始问题解释为并行/并发计算，而不是编程。

在并发计算中，两个计算都是彼此独立前进的。第二个计算不需要等到第一个计算完成后才能继续进行。但是，它并没有说明这是如何实现的机制。在单核设置中，线程之间需要挂起和交替(也称为抢占式多线程)。

在并行计算中，两个计算同时进行——字面上是同时进行。这对于单CPU来说是不可能的，而是需要多核设置。

图片来自文章:“Node.js中的并行vs并发”

与