Weapon Types are Changing
Back in the original Destiny game, the weapon types were broken down into Primary, Special and Heavy. However, in Destiny 2 they are now broken down into Kinetic, Energy and Power. It’s sort of the same thing, but this new weapon system will allow you to mix and match what guns you bring to a fight in a different way. For example, you could use a Hand Cannon in your Kinetic slot, but then add a Hand Cannon with Solar damage in your Energy slot. I’m not too sure why you would, but the point is that you can.