The way of describing this is that ablation is the cheaper easier option that the NHS default to, they use a laser and zap and burn the endometriosis, which is just treating the surface of the issue.
You have raft of gyane surgeons who are literally "having a go" at ablation, with minimal training, sending women home and saying take a few paracetamol.
The key take away from this is that the endometriosis isn't taken away it's just burnt, so recovery is fast, relief is simple and you get out of the system "fixed" the reality is 80% of the time you will end up with multiple surgery's. For years on end as it doesn't fix the problem and your insides are just getting burn and lasered.
Excision, this is only done by top excision specialist surgeons, and the surgery is done by removing the endometriosis by its root, its wide excision so an area around the endometriosis cells is removed, it's done in some cases with robotic assistance so it super effective and accurate, the NHS do have access to these surgeons but they a rare and have long waiting lists so you need to fight for excision only, wait or pay.
You can find the wide excision surgeons via google find who is local to you and insist you see them.
The recovery for this surgery is longer depending on the extent of your endometriosis, it's more involved, and took me 12 months to be pain free, everyone is different. But the chances of it coming back are as low as 20%.
The only way I've seen this explained is like shaving your legs or using an epilator..
Google Peter Barton smith and others and see what they say.
The other thing to note is endometriosis doesn't show on scans always.. I've have MRI,CT and vaginal scans zero Endo and yet with surgery removed from womb, ovaries, pouch of Douglas and bowels..
I hope that helps??