🤔 Wikipedia insists that a "21 Gun Salute" is different than a "Three-volley salute" because the 21-gun salutes actually involve up to 21 guns (not rounds fired), the guns must be cannons or artillery (not rifles etc.), and the subject must be honoring heads of state (not funerals etc.)

Yet the US Army is calling this a 21 Gun Salute on their YouTube: https://youtu.be/4fiPZBQqRFY?t=53

Honor Guard Performs 21-Gun Salute and TAPS

YouTube
Army Regulation AR600-25 appears to confirm Wikipedia's definition.