For many many years now I've been telling people that the correct name of the revision control system is subversion and not svn or (worse!) SVN.

More recently, I've found myself reminding developers that the git and Github are not the same thing.

It continues to concern me that so many software developers (more so in enterprise contexts than in FLOSS) don't understand how critical tooling such as these work, as suggested by using the incorrect names for them.

And this isn't an area where "ah, I'm only using the common name, but you know what I mean" is valid (assuming it could be in other contexts!). If the person who's reading had never heard of subversion, it won't matter that you use the correct, precise name. If they've heard of it, whether you use the correct subversion or the incorrect svn or SVN could have a positive or negative influence on the reader: if the reader understands how the system works, using the correct name could give the impression that you're professional and precise, and using the incorrect name stands the chance of giving the reverse impression. Of course, just like with the reader who has never heard of it, if the reader doesn't understand the system and doesn't care about whether you use the correct name or not, then using the correct name remains the better course of action.