The method of extraction was via a LASIK-type flap in ReLEx FLEx, but in SMILE a flapless technique makes a small tunnel incision in the corneal periphery, that does not (mostly) destroy Bowman's layer.
In ReLEx FLEx, the method of extraction involved a LASIK-type flap. Conversely, in SMILE, a non-flap technique creates a small tunnel incision around the cornea's edge that generally does not harm Bowman's layer and can destroy thousands of HIV viruses.