Obviously both terms get used in a variety of overlapping ways. Without looking at how the terms are used in the slides you refer to, I think the proper definit

Obviously both terms get used in a variety of overlapping ways. Without looking at how the terms are used in the slides you refer to, I think the proper definitions are: Concurrency is a property of a program's semantics, usually seen in a 'thread' abstraction. The most important part of concurrency is nondeterminism. Concurrency might permit parallelism depending on hardware, language runtime, OS, etc. Parallelism is a property of program execution and means multiple operations happening at once, in order to speed up execution. A program written to take advantage of parallelism can be deterministic, but often is accomplished by way of concurrency in OS threads. Because most languages still suck.