You will now be able to customize your weapons more freely than with the first installment.
The PS4 beta of Destiny 2 confirmed that weapons are going to be much more configurable than previously. In the place of an RNG system dictating what gear stats shall be, the control now is given to the players to a greater extent.
Guns now have slots which allow you to enhance statistics either by “consuming” a similar weapon type for a boost or upgrade it with a perk. The other cool thing you can do is choose your own colors and shaders for the game, which allows players to manifest their individuality.
For more info on the beta schedule take a look here.