[barrkel]

Determinism is making sure the digging is in the right place. Non-deterministic digging may be possible, but it's harder to get right.

Concurrency could also be having one guy with one shovel, but digging iteratively in 5 separate places and digging a shovelful or two at a time.

Or to put it another way, parallelism is digging two ditches with 4 people 4 times as fast as 1 person digging two ditches; concurrency is 1 person digging two ditches at the same time, alternating; determinism is making sure that the two ditches are being dug correctly, at an even pace, etc.