I wouldn't necessarily say they have better weapons. We've seen Warlocks and Titans wielding the same standard Assault Rifle Weapon, so it doesn't necessarily mean that Classes in Destiny are like Classes in Mass effect where they are heavily restricted. Of the base stats we've seen, there's Energy, Shields, Agility, and Discipline. I imagine that each of the three classes have different base values to help make the Flavor of the classes come to life, but those values should be modifiable in some fashion.