Variable, means that the interest rate being charged is charging based on the interest rate set out by the Bank of Canada. This rate fluctuates based on market conditions. Your payments will, with few exceptions, continue to stay the same however the amount you are paying will be distributed to the interest and principal in different amounts. If interest rates rise you will be paying off less of the original borrowed sum as more of your payment goes to interest. The opposite being true should interest rates drop. If you have a fair bit of flexibility in your budget, this may be a good option as variable rates over the life of your mortgage often result in lower interest charged.
Adjustable, as with the variable option above, interest rates will change with market conditions, however any change in interest rate will result in an increase or decrease in payment. This option should be considered with great care as an increase in rates could result in payments outside your budgetary limits.
As a mortgage professional I can help you decide which option is best for you by talking to you about current market conditions and expectations on future rate changes, as well as the risk you are willing to assume within your personal budget.