It's called a luggabeast and it is BOTH.
We know what it's called from Foster's novelization:
Reaching the top of a nearby dune, she found herself gazing down at a sight as curious as it was unexpected. Trapped in a net of local organic material, a small spherical droid was attempting to escape its prison, an effort rendered extremely difficult by the fearful mechanical’s total absence of limbs. Mounted atop a squat, four-footed, square-helmeted luggabeast, a native Teedo was struggling to constrain and reel in the legless but overactive and insubordinate droid.
Star Wars Databank says this:
Cybernetic beasts of burden found on frontier worlds, luggabeasts are a fusion of organic being and mechanical creation, with their heads hidden away behind heavy armor plating and optical instruments. Jakku’s Teedos use luggabeasts as pack animals, calibrating the cyborg creatures’ instruments to find droids and other valuable salvage.
Here's the image from Commando game (its use in military may explain the need for armor)