i am looking at getting one of these scopes. question is, what is the difference between the 1 inch tube and the 30 mm? tia

A 30mm tube may be a bit stronger and/or allow a wider adjustment range but, in all actuality, either would be fine. Obviously, the larger tubed scopes weigh more and require the use of appropriate rings. Burris makes decent stuff so I'd not worry... just select the one you like the best.