In addition to the extra units, Zero Hour originally intended to present the player with three (not merely one) boss generals in the Generals' Challenge, and include missions featuring General Fai and General Juhziz (which were missing from the final release). Playing the Generals' Challenge mode in unmodified versions of the game will eventually see the player stand off against a Chinese General named Leang, who commands the technology of all three factions at the end.
The game features dozens of generals (each with their own units, strategies, etc.) spread over the game's three factions. With that many generals, a closed beta sounds like a great idea to get all the balancing correct.