Adjustable - An Adjustable Rate Mortgage, or ARM, is a type of mortgage in which the interest rate is adjusted up or down, in accordance with current interest rate levels. The interest rates are tied to an economic index outside of your banks control, such as the Treasury bill rate. Your monthly principal and interest payment will fluctuate with these rate changes. Initially payments will be less than with a fixed mortgage, making this type of mortgage attractive to short-term buyers. Note: Inquire on the "cap", or maximum interest level your mortgage can reach, since it is possible for rates to raise significantly during the term of your mortgage.
Fixed - A fixed rate mortgage, on the other hand, uses both a fixed term (length of time) and fixed interest rate. At the start of the mortgage the rate and term are determined, and as a result the monthly amount for principal and interest payments remain constant for the duration of the mortgage. Fixed rate loans are more attractive to home buyers who plan on spending a long time in their home, or expect no major change in income.
Assumable - Sometimes homebuyers can find a loan which is "assumable." With an assumable loan, the current sellers lender is willing to transfer the existing loan to you, either at the previous interest rate or the current interest rate. Assumable loans are attractive to buyers because they usually require less paper work and less time.