DTG (Direct to Garment) works like this:
You need to pretreat (PT) your tshirt with pretreatment solution (definitely for black shirts, and some also do for white shirts to improve the print quality). You need to hand spray, or use a PT machine. This is a challenge for some customers.
Then you print to the Tshirt, and heat press to cure the ink.
DTG is the simplest approach, but it has a main drawback - the PreTreatment is challenging for many customers, and without a good pretreatment, the prints are not good.
DTF (Direct to Film) works like this:
Instead of pretreating the T-shirts, you use PRETREAT SHEETS ™ and PRETREAT POWDER ™. Some people also call these TRANSFER SHEETS and TRANSFER POWDER.
They are easy to use, and not challenging for any customer.
So you print to the PRETREAT SHEETS ™, apply PRETREAT POWDER ™, then cure (heat) so the powder sticks to the sheet. Then apply the sheet to the shirt, heat press, and remove the sheet. The process is a bit longer than DTG, but the success rate is higher as using PT SHEETS and PT POWDER is much simpler and higher success rate than PT SOLUTION used in DTG. Also, DTF equipment is cheaper, starting at around $2290 (for our L1800 DTF printer).
Quality of DTF prints is very similar to DTG prints.