I looked them up in several dictionaries, but still I can't figure out the difference. Could somebody tell me how to properly use these words?
Use definitely to describe something you don’t have any doubt about. If you are certain you're going to see your friend's band play, you can assure him that you'll definitely be there.
The adverb definitely is used to emphasize the certainty of whatever word it modifies. If you are sure you want apple pie, you could say you definitely want it. The base word definite can also mean "a certain limit," like the definite size a shelf must have to be. You wouldn't say "the carpenter definitely cuts the wood," to describe the exactness of the work; use precisely instead. AND, yes, definitely definitely has an e before the ly!
When something is absolute, it's total and complete. When something is absolutely the case, it's going to be that way — no ifs, ands, or buts.
When you want to be certain that there is no doubt about what you mean, then you say that it's absolutely that way. For example, there is absolutely nothing you can do that will make George Clooney invite you to his house on Lake Como. The moon is absolutely not made of green cheese. When I said that I would absolutely not go to that wedding, I wasn't kidding, and I didn't go. Absolutely can also be an interjection, a statement of emotion, as in, "Am I sure I'm up to it? Absolutely!"