The very quick answer is that Powerlifting is more about standing in one place and moving a heavy weight through a range of motion (be it deadliftdeadlift, squatsquat or bench pressbench press). There is a certain technique element to these lifts that can yield large jumps in weight (i.e. arching your back more on a bench press so the range of motion / distance you move the bar decreases).
Also, isPowerlifting requires one big effort for a single rep (though you do get multiple attempts).
Strongman is about moving big weights, sometimes rather unusually shaped big weights (i.e. Atlas stonesAtlas stones). Unlike powerlifting, there is a locomotion aspect to a lot of strongman events, picking. Picking up heavy stuff"stuff" and carrying it for distance or loading it onto something is a common eventin strongman events (i.e.farmers walksfarmers walks).
A lot of strongman events are also done for reps, distance, or time, as opposed to. Whereas powerlifting which is all about the total amount of weight. In a log clean and presslog clean and press event, you'll be given something like 75 seconds to clean and press a weight as many times as possible, which requires a surprising amount of work capacity / conditioning.
Also, powerlifting has competitions for lifters using powerlifting gear (squat suits, bench shirts, etc) and raw lifters. As far as I'm aware, strongman doesn't have the same restrictions.
Both sports have weight classes, though admittedly the most famous strongman events are open weight.
To someone starting out, I'd recommend concentrating on getting strong in the big 3 powerlifts as well as the overhead pressoverhead press, and also throwing in conditioning in the form of sled pushessled pushes / pullspulls and a lot of picking up heavy stuffpicking up heavy stuff and carrying it.