Concurrency(并发):

the term concurrency to refer to the general concept of a system with multiple, simultaneous activities

Parallelism(并行):

term parallelism to refer to the use of concurrency to make a system run faster

1. Randal E. Bryant and David R. O’Hallaron. 2010. Computer Systems: A Programmer’s Perspective (2nd ed.). Addison-Wesley Publishing Company, USA.