another word for these is railgun.

Technically, nope. While both use electromagnetic forces to launch projectiles, they work very diffently (kinda like comparing a normal gunpowder-based firearm to an RPG).

Gauss weapons (coil guns) use electromagnetic fields generated by a series of wire coils to accelerate projectiles - so yeah, magnets. The electromagnets (coils) need to be turned on / off with precise timing for optimal performance, and the projectile needs to be magnetic to actually be propelled.

Rail guns take advantage of Lorentz force by having two charged rails, with a conductive projectile in the middle completing a circuit. When A LOT of current is passed through, the interaction of the magnetic field produced and the charge flowing through the projectile accelerates it and shoots it down the rail.

Coil guns are something a hobbyist can make at home with enough dedication. Rail guns are what the military is researching as heavy artillery.