I hate how Volkl changes the names of their Vertigo series skis EVERY SINGLE FREAKIN' YEAR.
724EXS is about the same as the 724AX2 which would be about the same as the Vertigo G21, the Vertigo G20 and the Vertigo G2... 5 names for the same ski in 5 years...
The EXT is much softer and is suitable as a "first ski." Same as the 724AX1, G11, G10 and G1.
The EXP (AX3, G31, G30, G3) is more sidecutty and stiffer than the EXS and the Pro (AX4, G41, G40, G4, Vertigo, Snow Ranger, 7 names in 10 years) is the rock-star ski.