Borderlands had over 2 million weapons in the game, but many people complained how too many of the guns were too stale and didn't have much variety between them. Now gearbox is changing that by making the gun manufacturers from the first game feature new wepons, that are more distinctive to their brand.
Bandit
The Iconic bandits of Pandora have decided to go on to the arms dealing market. These weapons can be easily recognized for their squalid and makeshift theme, (i.e. a sniper rifle using a glass bottle for a scope.) While these weapons could lack in fire-power, they make up for having the largest magazine capacity in the badlands.
The new bandit weapons will have a "scrapped metal" look
If you're a fan of the modern age fps' like Call of Duty or Battlefield, then Dahl will have the weapons for you! These weapons will look more like realistic weapons than the guns did in the first borderlands and will have a better balance between power, speed and accuracy than other brand weapons.
These were rare collectible guns in the first game and they'll be returning for the second game with a yellow and white stripe theme to match Hyperion's famous robot assistant, Clap-trap.
From the name you can obviously tell they're Russian. This company specializes in automatic weapons like machine guns and rifles. Vladaf will have faster firing speed than any other manufacturer in Borderlands 2.
Tediore
These guys had a whole new revamp from there weapons. Changing from easy-to-use pea shooters, Teadiore guns have a Star Wars-esque look to them but there's more than meets the eye. If you run out of ammo firing a Tediore gun you can actually throw the weapon and it will explode just like a grenade. And the more ammo you have left in it the bigger the explosion. This definitely adds more strategy to your game.
A gun and grenade in one weapon! 
These tough bastards were known for making the biggest boom out of all the manufacturers in Pandora, that will still be true in the sequel. Expect these weapons to excel in fire-power and speed and to look very, very loud.
These guns were the best weapons to use if you chose the Siren as your class. All Maliwan guns had elemental tech so if you wanted to zap, burn, melt or even blow up your enemies, Maliwan was the choice for you. Expect this company to feature slick and futuristic looking guns, as well as all of them to have element attributes again.
My favorite manufacturer in Borderlands, Jakobs was famous for having the strongest weapons you can find. A good ol' Jakobs revolver could pop the head off a bandit from quite a distance if you knew how to use it. These guns will be retuning with an old western feel but will still boast in causing incredible damage.
I'm digging these weapons, seem better than the first one.