The breaker
A GFCI breaker protects the whole circuit from its first inch of wire — the cable in the walls, every receptacle, every hard-wired load. It has a white pigtail that lands on the panel's neutral bar; the circuit's neutral lands on the breaker instead, so the breaker can compare it with the hot. It is the answer for a pool or spa pump (NEC 680), a hard-wired dishwasher or disposal, a hydromassage tub, an outdoor condenser under 210.8(F), or a circuit whose first box is too shallow or too hidden for a receptacle-type device. It costs more per circuit, and a trip sends someone to the basement.
The receptacle
Protects itself and whatever is wired downstream of its LOAD terminals; the wire between the panel and the device is not covered, which the Code accepts because that wire is inside the wall. Cheaper, resets where the person is, and the natural choice for a bathroom, a kitchen counter run, a garage wall. One receptacle-type device per circuit run is usual; a second one downstream adds nothing but a second reset button.
Dual-function breakers
Where a room needs both AFCI and GFCI protection — kitchens and laundries since the 2014 edition in most adoptions — a dual-function breaker does both in one slot. A dual-function receptacle exists too.
Two-pole 240 V circuits
A 240 V load (a spa, a well pump, a dryer on a 250 V receptacle since 2020) is protected by a two-pole GFCI breaker; there is no receptacle-type device for the common 240 V configurations. Our 240 V in-line GFCI cords are the portable alternative for cord-connected 240 V equipment.
Nuisance
A breaker protecting a long circuit with several motors on it will see more leakage than a receptacle protecting one countertop. If a GFCI breaker trips with nothing obviously wrong, read trips with nothing plugged in before condemning it.