One is the Canadian Depository Receipt and the other is the US listed stock.
The Canadian Depository Receipt was created by CIBC to let Canadians get exposure to US stocks in CAD.
They are currency hedged, so you are not exposed to any movements between the CAD and USD. However, there is a fee of around 0.6% annually for this hedging.
I personally prefer to own my US stocks in USD, and I buy USD weekly. But, I do not blame people for owning these CDRs, especially those in retirement who primarily live off CAD. You still get exposure to the stock, but you get to keep it in your home currency and the currency you spend the most.