Hand-tied wefts are made by hand. They are generally thinner than machine wefts. The hand tied wefts must be reinforced right where you want to cut before cutting. Nail glue or super glue works great. Machine wefts are done by machine, they do not need to be reinforced or secured before cutting. Most have thicker weft, ONYC machine weft on the other hand is thinner and flatter than regular machine wefts hence lay flat on the scalp also. Machine wefts are made by sewing strands of hair together with a hair weft machine.