Huge difference between the two.
Cobra has 4v engine and forged crank, Saleen is a 2V.
Cobra has an IRS, Saleen SRA
Cobra has a T56, Saleen is a 5-speed.
The Cobra is the better handling and faster car with way better road manners. Also it can handle WAY more power and with simple bolt ons can make 500+ rwhp and well over 600+ with a twin screw. The Saleeen is pretty close to max hp untill you build a stronger bottom end.
Hope it helps