For an electric guitar, it involves just about everything. The guitar player in my band has a Fender Stratocaster, but has even changed the pickups to get his preferred sound. How they're wired is what matters (in the coils.)
He also uses a custom made American Carr amplifier with the obligatory glass tubular valves instead of solid state (transistor) circuitry.
Another factor is whether the guitar has active or passive wiring. (Active needs a battery to power the circuitry.)
Then there are the strings....... wirewound, flatwound, or a combination of both. Also, hollow or solid body for the guitar itself.
Acoustics can be large, Country style (Gibson Jumbo, Martin, Takamine etc etc), or classical Spanish types.......... steel or nylon strings etc.
Then you have the player himself... and everyone has their own style.
I've seen Pro, Jazz players pick up a cheap student model and get a terrific sound from it. Something a student couldn't get anywhere near.
It's a case of taking all these parameters and combining them. Literally thousands of combinations.
With Rock guitarists, the preference is usually for "old-fashioned" valve amps such as Marshalls.