Extra Attacks Weapons with [EXTRA ATTACKS] in their profile are known as Extra Attacks weapons. Each time the bearer of one or more Extra Attacks weapons fights, it makes attacks with each of the Extra Attacks melee weapons it is equipped with and it makes attacks with one of the melee weapons it is equipped with that does not have the [EXTRA ATTACKS] ability (if any). The number of attacks made with an Extra Attacks weapon cannot be modified by other rules, unless that weapon’s name is explicitly specified in that rule.
Assault Weapons with [ASSAULT] in their profile are known as Assault weapons. If a unit that Advanced this turn contains any models equipped with Assault weapons, it is still eligible to shoot in this turn’s Shooting phase. When such a unit is selected to shoot, you can only resolve attacks using Assault weapons its models are equipped with.