[ncmncm]

The article uses the term "parallelism" when it is talking, instead, about concurrency.

Parallelism is specifically the stuff that actually does happen completely independently on all processing units, that actually goes Nx as fast on N units (clock depression aside). Concurrency refers to the overhead of coordinating activity of those units, that keeps you from getting your Nx. It is overhead on top of any actually serial parts of the computation, which Amdahl's law addresses.

In other words: Parallelism giveth, and concurrency taketh away.

The distinction gets more useful the more you think about the subject.