I believe they are. The TSA may have more flexibility in their ability to move people from one area to another in a time of need. If there was an incident in one area of the country, they could reassign people from one to the other. With CATSA, if they have one security provider in one airport and a different provider in another airport, they can't move them between because of the contract.
On May 6th, 2010. See this statement in context.