Question on book for U.S. history

<p>Is the AP Princeton 2006-07 edition ok to study (i dont have the money to buy the subject test version. Whats different about it). Is it ok to use? how is the AP different than subject (other than essays).</p>

<p>AP test is harder than subject test because it has an essay.
other than that the AP mult. choice = SAT II USH mult choice.</p>