Non-Generic Red vs. Blue is a 25v25 experience based around fun and varied gameplay and locations. Nearly every item in Creative is available for you to use right from the get-go; no timed vaults, Gold shops, nothing, allowing for you to create some wacky loadouts!
Items are also "balanced" via rarities and a powerful items mechanic, making it so there is an incentive to use other kinds of items without directly nerfing them.
A 25v25 Red vs. Blue based on the idea that you can play how you want at any time with as much fun as possible; nearly every item in Creative is available for you to use, with no restrictions such as vaults that prevent you from getting them from the start.
Items are also "balanced" via different rarities per item, no overpowered mechanics such as power-ups, and a Powerful Items area, so there is an incentive to use other kinds of items without directly nerfing them.