(What's the difference between a piano and a keyboard?)
The size and weight of the instrument is the most important difference for our purposes!
If it sits on a separate stand, is plugged into a wall, and can be moved by one person, it's a keyboard.
If it resembles a piece of furniture and requires heavy lifting, it's a piano. Most pianos are acoustic (not electric) but some are digital (electric). Both acoustic and digital pianos require anywhere from 2 to 6 people to move.