Our industry is rife with TLAs and DFLAs (three-letter acronyms and dang four-letter acronyms), from way up in the realm of the CEO to way down in the realm of the ROV and the BHP.
Generally, initialisms are abbreviations made up of the first letter of several words, such as EU, UK, USA, UAE or SPE. These do not have periods after each initial.
Acronyms are initialisms that form a word or are pronounced as a word, such as NATO or OPEC. These “true acronyms,” where each letter stands for a separate word, are written in all capital letters.
“False acronyms” are made up of parts of words, rather than just the initials, such as Aramco (Arabian American Oil Company), Capex (capital expenditure) and Opex (operating expense). These false acronyms capitalize the first letter and use lower case for the rest.
Of course, there are exceptions to the false acronyms rule, mainly in the trademarked software names, such as COBOL, FORTRAN, BASIC, UNIX, dBASE, STARS, and MS-DOS. In that case, go with the trademarked capitalization.