It really depends how far up you are right now, some A shows time your course and add to your time by faults (dropping a pole, wrong lead, etc.) But if it is just state wise showing you really shouldn't see much of a difference with the exception of more shorts, and tee shirts.
I don't know the rules of IHSA, I have friends who show in it so I will try to help. If you are doing the hunters, we usually braid for A or AA shows. Read the rules for the division you will be showing in, they will usually tell you what is allowed for the division. The classes are usually quite large as well. Let me know if you have any other questions.