The fixed rate is a rate that does not change for the duration of the chosen term. It offers peace of mind and protection against future increases.
The variable rate changes throughout the term depending on the market. It generally has the advantage of being lower than the fixed rate at the time of signing. It is however more risky because it can rise at any time during the term.
The mortgage credit line benefits from a lower interest rate than a regular line of credit. It also allows you to get additional money as the mortgage decreases. It is very flexible but requires a good budget management.