First be prepared! College bookstores are crowded with students and books are tossed all over. Seems like schools also use obscure ways to organize books.
Then there is the cost. You might find other bookstores or notices on bulletin boards. Nevertheless, expect sticker shock.
When I was choosing books, I based my choice on how topics were organized, graphs and other visual aids, indices that were easy to use and so forth. If things were equal, I chose the cheaper book. Which textbook to use is based on personal choice.
Mea culpa, but once I even chose on on the co!or of the cover that matched the color of my car. There are favorite books, but none are perfect. The the textbook is the primary tool for a class. Therefore, their may be ways to choose something different. You may find that there is an earlier edition with minimal difference. If the dates of publication are close, the organization is very similar and the price was good, I would probably choose that one. If I didn't find how ideas were explained, I would find one in the school library