To quote Panasonic-san: coin type lithium batteries are available in two types: poly-carbonmonofluoride lithium batteries (BR series) for uses that require extended reliability
and safety, and manganese dioxide lithium batteries (CR series) for uses that require high voltage and strong load pulse characteristics.

So essentially either can be used. CR types probably have slightly higher capacity and better current supply characteristics, so may last longer. But not by much.