What is the difference between i.e. and e.g.?

I.e. means 'that is' (to say). E.g. means 'for example'. I.e. is an abbreviation for Latin id est, 'that is'. E.g. stands for exempli gratia, 'for the sake of example'. So you can say, "I like citrus fruits, e.g., oranges and lemons" (for example, oranges and lemons) or you can use it to mean "I like citrus fruits, i.e. the juicy, edible fruits with leathery, aromatic rinds of any of numerous tropical, usually thorny shrubs or trees of the genus Citrus," (that is to say, the juicy, edible fruits...). In the first sentence you are simply giving an instance of a citrus fruit; in the second you are giving an explanation. E.g. indicates an example; i.e. specifies and explains. Compare: She loves to read non-fiction, e.g., reference books and how-to books. / He had one obvious flaw, i.e. his laziness.

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