'Wonder', used to mean fascination, is much more intense. It indicates that not only am I interested, but I am excited and fascinated. If I show interest in something, it means that I have some curiosity or concern about it, but it would not necessarily mean that I am excited and in wonder about it.

Wonder you are trying to describe a situation where something you like to happen. Interest is the word commonly used when there is something you need to answer precisely and done more frequently from you end.