There is a difference between Duct Tape and Gaffer Tape. Duc Tape looks similar to the Gaffer Tape. I will explain:
Duct Tape can be used for carpets or other uneven surfaces. It is a popular choice because you can use it for almost anything. However, it has a stronger adhesive than Gaffer Tape.
GafferTape can be used on a variety of surfaces, such as vinyl, wood, ceramic, plastic, aluminium and steel. However, the Gaffer Tape can be removed cleanly, leaving less residue than the Duck Tape. Unlike Duct Tape, Gaffer Tape can be applied easier than Duct Tape because it can be torn both ways, both on its length and width.
In conclusion, both Gaffer Tape and Duct Tape are good, the only difference is that Gaffer Tape leaves less residue and can be applied better than Duct Tape.