It's not a critical difference, but if you're around people that are sticklers for technical accuracy, it helps to differentiate between them.
The term "handguns" can be used to refer to revolvers and semi-auto pistols in the aggregate, but when referring to them individually, I like to used the proper terms. I even go so far as to specify DA or SA when talking about revolvers.
I'm sure my 1911 style Llama (a good one) in .380 is SA. I have no idea whether my carry revolver (inherited from grandad) is SA or DA. The thumb on the hammer cocks it as it clears leather. It's automajik. What is the point of DA?
/johnny
There’s another reason. Newbies have enough trouble getting an understanding of firearms. There’s no reason to further confuse anyone just because someone wants to sound like an expert.
One of my first purchases was the book “Cartridges of the World”. When I found out there was half a dozen copies at a half price bookstore I bought them all. I sold them at cost to my friends. The only problem I found was there is never a listing for 4MM rimfire Flobert.