A fixed rate will remain the same for the term (6 months – 10 years) of your mortgage. The benefit here, is your monthly mortgage payment will remain the same for the duration of your term and a predetermined amount of principal and interest will be paid.
A variable rate will fluctuate with the market. The benefit of a variable rate is, it is often lower than a fixed rate at origination. However, it is subject to change at any given time. Your monthly payment will remain the same but the amount being paid toward principal and interest will change. With an adjustable rate mortgage, the rate will also fluctuate with the market, but your monthly payment will increase and the principal and interest portion will remain the same.