Scaffold Resource uses products chosen specifically to meet the unique requirements of each job. When dealing with a structure as historic and noteworthy as the Mid-Hudson Bridge, Scaffold Resource made sure to protect the bridge itself as well as the travelers below.
GFCI (ground-fault circuit-interrupter) protection is required for many receptacles (outlets) throughout the house and outdoors. This protection can be provided either by a GFCI breaker or GFCI receptacles. There are advantages and disadvantages to each approach, depending on the installation.
None of them really defines a GFCI. I'd also say that none of them is strictly true. A GFCI is basically a device that checks whether the current flowing through one side of a circuit is equal to the current flowing through the other side, and mechanically opens the circuit when they aren't equal.