This is a long standing gripe - but I feel if I at least write it down that will go some way to getting it off my chest.
Both acronyms and initialisms are abbreviations, but there is a key difference between the two, at least at present. Due to rampant misuse of the term “acronym” some dictionaries are now starting to add an extra definition to it, allowing acronyms to expand their scope to include initialisms. So as the English language evolves, this additional definition of acronym may stick and become widely accepted. But at present, it’s generally still good form to distinguish between the two. - Source
Bottom line - acronyms are different to initialisms - but it's so widely misused it seems the battle is lost...
Lets look at the definition for each -
Acronym an abbreviation formed from the initial letters of other words and pronounced as a word (e.g. ASCII, NASA ).
Initialism - an abbreviation consisting of initial letters pronounced separately (e.g. BBC ).
There's a key difference there - acronyms are pronounced how they are spelt. Initialisms are not. NASA, NATO, LASER, COBRA etc . etc. - they are acronyms.
FBI, CIA, NHS, DWP etc. etc. are not. They're initialisms.
So there you have two distinct words - with different meaning - but the whole world is happy to carry on using the wrong one... it's not a major problem. It doesn't bug me every waking hour of my life - but it bugged me enough to spend 15 minutes writing this!