If everything goes well, there is really not much difference at all in the safety or visual outcomes.
All LASIK involves 2 steps: 1) Cutting a very thin flap from the surface of the cornea, and 2) removing some of the underlying cornea in a precise manner so as optimize the focus of the eye, then replacing the flap.
This was originally done mechanically with what resembled a microlathe containing a steel blade. The variability in thickness of the flap was occasionally an issue as was centration. If a second treatment was needed (more common in the early days than now), the edge of the this kind of flap could sometimes re-heal poorly.
Most LASIK today uses a femtosecond laser to cut that flap, which is more precise and without the beveled edge of the mechanical keratome (microlathe), making for a better seal at the edge.