Acronym vs. Abbreviation vs. Initialism: What’s the Difference? 

An initialism is another type of abbreviation similar to an acronym—but not exactly the same. Initialisms also use the first letter of each word in the phrase, but instead of combining the letters to form a new word, like with “NASA,” you pronounce each letter individually. Here are some examples:

• VIP, which stands for “very important person”
• DVD, which stands for “digital versatile disc”
• ATM, which stands for “automatic teller machine”
• AM and PM, which stand for “ante meridiem” and “post meridiem”
• RSVP, which stands for “répondez s’il vous plait“

Technically, acronyms and initialisms are types of abbreviations. Not all abbreviations, though, are acronyms or initialisms—those terms refer to specific types of abbreviations formed from taking the first letters of words in a longer phrase or name. 

The real confusion comes when determining which of those types of abbreviations are acronyms and which are initialisms. Since initialisms are similar to acronyms, many people say that “acronym” can be a blanket term that also covers initialisms, as yourdictionary.com points out. A lot of people do use the word “acronym” to refer to an initialism that technically is not an acronym because it’s not pronounced as a word.