They are acronyms. Why do you think differently? And acronyms are abbreviations. If you want to argue more you could state they’re initialisms, but SAN is standard algebraic notation so it’s definitely an acronym, while EPD could be argued not, but instead to be an initialism. In any case Wikipedia says it’s not a settled matter so why even argue about it?
https://en.m.wikipedia.org/wiki/Acronym
I’m not OP, but I’ll answer the question for me. I think differently because I was taught differently in English class about 40 years ago. The wikipedia page makes a weak argument.
What do you think distinguishes an acronym from other abbreviations?
Acronyms and initialisms are formed by each of the first letters of a phrase. Acronyms are distinguished from initialisms by being pronounced as a word rather than saying each letter individually. Abbreviations are shortened words or phrases: apartment=apt., captain=cpt., corporation=corp., minute=min., etc.
