This is from a review on Amazon regarding the differences bet 9th/10th edition:
"I would like to address the 3 biggest changes;
1) The actual text of the 10th ed. biology 1 book, now labeled "biochemistry" instead of "biomolecules" has included some more extensive research and content.
2) The Psychology & Sociology book in the 10th ed. has been amplified with more terms and sufficient content.
3) The five science books now have updated 30-minute exams. Instead of just 3 passages, it is now 4 passages and 5 discrete questions per chapter exam. The first 3 passages of the science books are no different from the 9th and 10th ed.
The other four books; Physics, Chemistry, Biology 2, and Verbal Reasoning seem to be nearly 85% identical to the 9th edition. I will note that the verbal reasoning strategy has had some changes that were noticeable, especially in chapter 4. Basically, EK seems to have updated their verbal strategy"