Sometimes the paper can be thinner. Sometimes it's in black and white and the US edition is in color. The international edition is almost always softcover and the cover may be in Chinese (for instance). The problem sets may be in differing order.
Many of these things are described in the comments. I almost exclusively buy international textbooks for home reference if available. The price difference and the relatively small quality difference makes it a no-brainer. If you are doing it for a class though, find a friend with the overpriced version for homework.
Many of these things are described in the comments. I almost exclusively buy international textbooks for home reference if available. The price difference and the relatively small quality difference makes it a no-brainer. If you are doing it for a class though, find a friend with the overpriced version for homework.