"Pragmatic" connotes a choice that achieves a goal by practical means, possibly sacrificing some desirable features that are challenging to achieve.

"Expedient" connotes a choice that achieves a goal quickly and conveniently, possibly by sacrificing some important but difficult features, and incurring some undesirable costs or consequences.

So they're similar, but not identical. A pragmatic choice might be improved when you can afford it. An expedient choice will probably require some cleanup afterward.