After taking the (only available) mock test, it seems to me that the TOP differs from the HSK in that the vocabulary is narrower in scope, but requires a more precise comprehension of each word and phrase than does the HSK. The multiple choice answers in many cases only have subtle differences separating right from wrong, or right from not quite as right.

I did find a vocab list on YellowBridge

http://www.yellowbridge.com/chinese/fc-engine.php

I do like the practical focus on the test - reading comprehension taken from actual, or at least realistic looking, documents and adds.

I still maintain hope that the HSK will be offered in Chicago before too long.