Campbell 7th vs Campbell 9th?

<p>I'm using the Campbell Biology textbook for my college bio class.</p>

<p>I already have the 7th edition, and so I don't really want to buy the 9th edition that the class uses. </p>

<p>For those of you who have seen both editions is there a difference, apart from the obvious layout change? </p>

<p>Thanks in advance.</p>