What can fix gummy smile? Gingivectomy vs crown lengthening?

Both. They are basically the same procedure. A crown lengthening may involve bone removal too while a gingivectomy is just soft tissue removal. Both will make the teeth appear larger.
Both and more. Gummy smile can be improved with both gingivectomy and crown lengthening. Other options may be botox, orthodontics (braces), or jaw surgery. Every case of gummy smile is different. Talk to your dentist about the treatment that is appropriate for your specific case.
Different procedures. They are two different procedures for two different circumstances. A gingivectomy only removes gum tissue while a crown lengthening procedure requires the removal of bone. You should consult with a periodontist who can clinically examine you, along with your x-rays to properly advise you what is best for your specific situation.
Botox or not. Botox is the least traumatic procedure option. Just 2 properly placed injections can help drastically.

Related Questions

How does a gingivectomy differ from a crown lengthening?

A gingivectomy . Is limited to trimming (recontouring) off the gingival tissues (soft tissue only) a crown lengthening in addition to the above also involves trimming off some of the underlying bone so as to reflect more of the tooth's clinical crown. Read more...
What tissue. A gingivectomy is the removal of gum tissue only. Crown lengthening is a procedure that typically involves the removal of both gum and bone to expose more of the tooth. Read more...