How much do different textbook editions typically differ?

Question

I need the 10th edition of a particular textbook for one of my classes. I ordered it, but it was lost in shipment, and my money was refunded because the book was out of stock. So I checked out the 9th edition from my school's library as a temporary substitute. But so far I have been pleasantly surprised with how well it goes along with the homework we've been assigned...so, should I buy the right edition, or could I probably get by with the older one and save some dough?

Answer 1

They're usually pretty similar especially since your editions are so close I think for the most part you'll be ok. However, my experience is that sometimes content on different page numbers change because of the new revisions they've made so be careful about that.  

Answer 2

Ask your teacher.  I have a teacher who said that we need the twelf edition of a specific book but saw a student with the 11th and said that if we already purchased the 11th, than it should be fine.  The higher the edition, the more updates it has.  So ask your teacher, he or she would be the one who would honestly know.