We assume you mean that a mobile home is used, and a manufactured home is new...but in either case if you are getting a loan then, yes, you would need to get a credit check and your credit will need to be pretty good (especially now).
Credit is not everything when buying a home (either mobile or manufactured). Income and downpayment are more important.
Real Estate in general is not going up any time soon, so take some extra time to get your credit in better shape, save extra money, etc. to get in a better position to buy.