[Edicius]

The main difference between a Gundam and a regular mobile suit is the armour.The orignal Gundam, the RX-78,was made from a lunar titanium alloy. Most mobile suits at that time where made from titanium alloy or a super hard steel alloy. Originaly a Gundam was only a Gundam because it was made of harder metal and was able to wield beam weaponry with greater efficeincy, it really only slightly outperformed a reglular mobile suit, it was generaly an exceptional pilot that made it such an uber machine.

In the AC timeline however a Gundam is a Gundam because not only is it made from an alloy called Gundanium (regular suits are still made from titanium alloys), but it generaly has some sort of advanced computer system that allows the Gundam to interface with it's pilot, making the machine like an extention of the pilot's own body. It's a bit more over the top than the original Universal Century timeline's concept, which didn't get really wierd untill they started building machines for Newtypes and mobile armours and all kinds of odd things.

In any case it's still the pilots that make most of the difference. In 08th MS team you see entire squads of Gundams get taken out by a handful of Zaku IIs and in Gundam Wing Zechs Merquise literally pilots a museum piece but still gives the Gundam kids a hard time.