[neogodless]

https://www.wordnik.com/words/acronym

But... an initialism is an acronym. So it's both.

> an initialism is an acronym that is pronounced as individual letters

EDIT: Guess it depends on the source; even my link above says an acronym is "a pronounceable word", but another link I had clicked on had the quote above. shrug

[dspillett]

I was taught the other way around: an acronym is an initialism that can be pronounced as a word, all acronyms are initialisms but not all initialisms are acronyms.