Guitar tone is the sound or timbre of the guitar which could mean the effects that are being used, what pickup selection is being used, is it played with a plectrum or fingerpicked, and many other factors. You could say that the sound difference between an acoustic guitar and electric guitar is due to the difference in tone. Or the difference between Kirk Hammett’s distorted guitars in Metallica and Mark Knopfler of Dire Straits’s clean to lightly overdriven sound is due to differences in tone.