As a general rule, the difference between SPE 115 & SPE 125 is that one of them is Interpersonal Communications and one is Speech. They are both good classes to take. Several years ago they were considered equivalent classes at many colleges & universities; this is no longer true. If you have to choose one course or the other, you're best bet is probably Speech. This one is a requirement in almost every major, whereas Interpersonal Communication is a good idea, but not necessarily a requirement.