Resources - High Ratio vs Conventional Mortgages
The difference between a High Ratio and a Convetional Mortgage is determined by your down payment. A mortgage is called a high ratio mortgage when the down payment is less than 20% of the purchase price. Another way of saying that is that the ratio of the mortgage to the purchase price is greater than 80%, hence "high ratio". 

The current maximum amortization for a high ratio mortgage 25 years. Home buyers who are purchasing a primary residence with less than 20% down payment will have to pay an insurer premium to have the mortgage insured with one of the 3 insurers (CMHC, Genworth and Canada Guaranty). The insurer premium can be added the to mortgage amount or paid up front on the closing date. It is more common  for it to be added to the mortgage. 
Conventional mortgages are those where the total down payment is at least 20% of the purchase price for a primary residence, and as such avoid paying the insurer premium. By putting 20% down the home buyer will have a lower mortgage but can also take advantage of a 30 year amortization which lowers the mortgage payment verus a 25 year amortization on the same mortgage amount. Some lenders also offer 35 year amortization, for more information on this please contact one of our mortgage agents.