They might have the same software, I don't know, but the interface is cleaner (CT has a black background which burns a lot of people's eyes against other white background webpages), the navigation is simpler to a new user (in my perspective), things are easier to find, and the classifieds did not cost credits/money (this might have changed recently, but you had to pay to post in the classifieds on CT for a while). CT also offered membership subscription plans, with added site benefits, which went down the drain because due to personal problems, the owner did not provide such added benefits.

A good website with enough users should be able to sustain itself with ad revenue, IMHO.