Quite often, "i.e.," and "e.g.," are thought to be interchangeable. However, they do mean different things. So what is the difference and why aren't they synonymous? "i.e.," is the abbreviation for the Latin "id est," which translates as "that is." "e.g.," is the abbreviation of the Latin "exempli gratia," which means "for example." "i.e.," should be used when you want to clarify something by using different words. "e.g.," should be used when you simply want to give one or many examples of what you are expressing. See the sentences below to get a better understanding of the comparison. The mall is packed with clothing stores, e.g., Nordstrom, Macy's, Cache, and Ann Taylor. Today I'm going shopping at the best store in the city, i.e., Crate & Barrel.
~Reinforcing Proper English by Reviewing Punctuation, Grammar, and Spelling Rules