What is the Difference Between Similar But Different Things, Terms, and Objects

What is the Difference between Mnemonic, Initialism, Acronym and Abbreviation

Getting rid of difficulties is not just the passion, but the necessity of mankind. People try to make everything easy, so that it could be memorize and speak easily. You know well that there are lots of phrases and chain of words that describe only one name, but we make them short to remember them easily.