The short answer
If the product is fabric and it can take heat, garment DTF is usually the simpler route. If the product is a rigid or heat-sensitive object, or a finished item you cannot put in a press, UV DTF is the process designed for that job. The two are not interchangeable: the inks and the films are different, and a transfer made for one process will not work in the other.
Garment DTF: print, powder, cure, press
Garment DTF prints pigment ink onto PET transfer film in CMYK plus white. While the print is still wet it is coated with hot-melt adhesive powder, and that powder is then cured. The finished transfer is placed on the garment and bonded with a heat press.
The white ink channel is what makes DTF work on dark garments: it lays an opaque base under the colour so the design reads correctly on black or navy fabric. The heat press is a required part of the process, which means the substrate must tolerate the press temperature and pressure.
UV DTF: print, cure, apply with pressure
UV DTF prints UV-curable ink onto AB transfer film. The ink cures instantly under ultraviolet light, and the cured print carries its own adhesive layer. Application is by hand pressure or a cold laminator, not by heat.
Because no heat is involved, UV DTF can decorate glass, metal, plastic, coated board and finished products that would be damaged or distorted in a heat press. It is the process for decorating an object rather than a textile.
Where the two overlap, and where they do not
Both can put a durable full-colour graphic onto a surface, and both use a transfer film, which is why the names are similar. The differences that matter operationally are the curing method, the adhesive, and the equipment each one requires.
Garment DTF needs a shaker, a curing step and a heat press, so it carries a larger footprint and a finishing workflow. UV DTF needs the printer and a UV curing capability, and its finishing step is application pressure rather than heat. A shop selling decorated apparel and a shop selling decorated drinkware are running two different production lines even if both use a machine labelled DTF.
Choosing between them
Ask what the customer receives. If it is a garment or a textile item that tolerates heat, garment DTF gives the softer hand-feel on fabric and the established wash behaviour. If it is a rigid object, a heat-sensitive item, or a finished product you cannot disassemble, UV DTF is the only one of the two that can be applied at all.
If you sell both, they are complementary rather than competing: one line covers apparel, the other covers hard goods, and they share the design workflow even though the consumables are separate.