I’m not ashamed to admit that, up until “not too long ago”, I struggled with differentiating parallelism from concurrency in the context of computer programs. Don’t get me wrong, I wasn’t completely oblivious to the concepts - I understood them to some extent. I just couldn’t explain or differentiate them to a five-year-old or a recruiter in a technical interview.

I was reading a stack overflow comment(not to be confused with an answer) where the user explained, in very few words, the differences between the two concepts in the simplest way imaginable (at least IMO). It was a Eureka moment for me.