What are the differences between Canadian VNCs and US Sectional charts?
The short answer is the charts are different because they're made by different groups - NAV CANADA has different charting standards than the FAA/NACO uses.

Similarly Jeppesen makes VFR charts for the United States, and they look very different from a FAA/NACO chart:

I have charitably described the Jeppesen VFR+GPS charts as "technicolor puppy vomit" on more than one occasion.



As far as I'm aware there's no comprehensive listing of all the differences between the US VFR Sectional format and the Canadian VNC format, but the NavCanada charts have a legend and there Canada Flight Supplement (CFS) contains a great deal of additional information - it's essentially similar to the US Airport/Facility directory.

Unlike the US charts, Canadian Aeronautical Charts--including the VNC--do not have a specific expiration date. They are revised periodically.