Two different processes ... both processes require a special type of printer, special ink, special transfer paper, and a heat press.
Inkjet Transfers are printed onto special Inkjet transfer paper using an inkjet printer. Then you take the printed image and heat press it onto the garment. Quality varies depending on the printer, ink, transfer paper and garment type. The image will usually fade over time and with frequent washes.
Dye Sublimation prints are also created by an inkjet printer, using special Dye Sublimation ink, RIP software, and special Dye Sub transfer paper (not the same as the inkjet transfer paper). You then take the printed image and heat press it onto the garment (white or light polyester ONLY). Quality is outstanding, but the learning curve is much steeper. Using the proper Color profile is critical. The image will never fade, crack, peel, or washout (the white or light poly fiber is actually dyed).