Academic vocabulary is pretty specifically the type of words that you are likely to come across in TOEFL tests as well as ACT and SAT tests.
In general, most conversation and a great deal of reading material does not contain a lot of academic vocabulary. To study for a Toefl test or another standarized test, you will be reviewing many words that will never come up in everyday conversation. This can be a little confusing, especially for ESL students, who might do very well on academic tests and then have a problem with conversation skills or comprehension of text skills. That is because normal conversation is much different than academic text and requires different skills to understand. Well, that's what learning a language is all about. More later! Courtney W., MA