Any type of creditor agreement that isn’t guaranteed by a government-backed program, like FHA, VA, or USDA would be considered a Conventional loan. They are backed by government-sponsored entities Fannie Mae (FNMA) and Freddie Mac (FHLMC).
There are two different types of Conventional loans: conforming and non-conforming. A conforming loan is backed by government-sponsored entities Fannie Mae (FNMA) and Freddie Mac.
Any loan that does not meet these criteria is a non-conforming loan.