A tube amplifier hides fragile glass vacuum tubes seated in sockets that a hard impact can knock loose or crack, while solid-state amps mostly just need to stay upright and padded. Knowing which type you have changes how carefully you need to handle it.
Pro tip: If you remove tubes for extra protection, mark each one's position with a piece of tape before pulling it, since tube types sometimes differ by position and reinstalling them in the wrong socket can cause issues.
Watch out: Never stack heavy boxes on top of an amplifier; the speaker grille cloth and control knobs are easily crushed, and a caved-in speaker cone is an expensive repair.