The major difference is that the Pro Carry is a 4" barrel, while the Ultra carry is a 3" barrel. Some of the Pro Carry series give you the option of 9mm or 45. While the Ultra Carry (I believe) only gives you the option of 45. Either is an excellent choice. If it were me I'd stay with the 45, I've never been able to comprehend a 1911 style handgun that was any other caliber.