Open mortgages often have higher rates, but allow you to make changes to your mortgage payments without restriction. An open mortgage also allows you to make unrestricted lump-sum payments to reduce the principal of your mortgage.
Closed mortgages generally have lower rates than their open counterparts. They are the most popular choice in Alberta. You can usually make some increases to monthly payments or make lump-sum payments, but the amounts are restricted and penalties for overpayment could apply.