Digital pianos usually have the full 88 weighted keys, just like a regular piano. They’re a nice alternative to an acoustic piano if you want a different sound. These are the most similar to a piano and a great way to start your child learning on something that doesn’t take up as much space in your house.
On the other hand, a keyboard is very portable and includes extra features. While they often have an acoustic piano sound option, they’ll also have plenty of other sound options, including rhythmical accompaniments and drum rhythms. They often have built-in songs, too. Keep in mind that the sound quality won’t be as realistic as a digital piano.