tl;dr: People have answered your question about the difference between a digital and acoustic piano, which is your second question in the body text. I'll answer the question in your title What is the difference between a digital piano and a keyboard? acoustic one? Marketing. And some functionality. I want to be able to play with headphones so I can play at any hour, can you do that on a digital piano? Yes, subject to the caveat that some digital pianos have keys that are pretty "clicky" or have other sound that's projected when you're playing them. So you'll want to check the particular model depending on how quiet you need it to be. The long answer: Electronics manufacturers generally market digital pianos as substitutes for acoustic pianos. They generally have 88, full-sized keys that are to some degree weighted to make them have a touch that more closely resembles a piano. (The best ones have heavier weights on the bass keys, and lighter weights on the top high keys, known as "graduated weighting.") They generally have fewer built-in sounds than a synth or keyboard (discussed below). They generally have built-in speakers, and more expensive digital pianos will have better built-in speakers. Some will be more furniture-like, with a built-in stand and sometimes even built-in pedals. There will be generally fewer "electronic fiddling" options (see below) -- but I don't know of any digital pianos without a headphone jack. Most will have a few other tech options, like MIDI in and out, easy transposition options, and sound mixing. They can get very expensive, especially if they acts furniture and an instrument and have really high quality sounds in them. A "keyboard" is a more generic term for any keyboard instrument. Most of the time, very cheap piano substitutes are called "electronic keyboards." The quality, features, feel, and cost of these instruments vary WILDLY. Technically, a keyboard with built-in sounds is called a "synthesizer," and one without any sounds, but that relies on an external source to provide sounds, is called a "controller." Unless you're in a music production studio, you generally don't want a controller. Basic keyboards will generally not be 88 keys, and they'll be weighted very differently from a piano, with a springy, fast moving feel. Even high-end synth keyboards may not have weighted keys or only semi-weighted keys, because professionals playing those instruments are more likely to play them like an electronic organ (which has different fingering, technique, and style than piano playing). Keyboards / synths that are touch sensitive may not have as sophisticated of electronics to measure the velocity/pressure/aftertouch (don't worry about these concepts) as a digital piano. Keyboards/synths often have way more on-board sounds (though often the quality of the actual sounds will be lower, see below), and way more on-board methods of playing with the sounds, with things like pitch wheels (to make the pitch of a note go up or down) mod wheels (to add things like reverb or tremolo), mixing options, and the like. Cheap keyboards also often have cheap "shortcuts" on them-- rhythm backgrounds, shortcut ways to play chords, and the like. Have you ever seen the funny "I Wish It Was Christmas Today" skit from Saturday Night Live where Jimmy Fallon plays the keyboard? That's a relatively cheap keyboard that comes with onboard "one-finger" chord changes, rhythm backgrounds, and multiple sounds. https://www.youtube.com/watch?v=jDdSQlCbJ90 But it doesn't sound very good. That's the point of the joke. They keys also don't react like a piano. It wouldn't be very satisfying to play a piano piece on. On the other hand, digital pianos are often more expensive (comparing equivalent levels of quality), heavier, harder to transport, with fewer of those creative options. ONE MORE THING -- I mentioned the quality of the "actual sounds" above. So keyboards generate music in one of three ways. The first is by using mathematical computations (or, in the real old school, switches, diodes, transistors, and other semiconductor devices) to create particular types of sound waves. Then, a computer (or another old school switch) adjusts the frequency of the wave when you press a key. Most of the time the sounds produced using this method sound like "synth" sounds -- imagine the beginning of "The Safety Dance" by Men Without Hats, or "Jump" by Van Halen. The second way is that the keyboard/piano has a memory card that stores recorded sounds from an analog instrument (called "samples") and replays them when you press the key--every note is sampled from the original instrument and simply recalled at the right volume when you play. The quality of the instrument, then, really depends upon the quality of the recording of those sounds and the ability of the instrument to reproduce them. The best digital pianos, and very expensive "stage pianos" (keyboards that are more portable but whose job is to replicate a piano on stage, like in a rock band), do this. The third way is a hybrid--the keyboard/piano has a memory card that stores just a few "samples" from the instrument and then uses math to adjust the pitch when you press different keys. So, for example, for a piano sound, the manufacturer might store a sample of a note below low c (c3), a note in the normal bass range (maybe g3), then middle c (c4), then maybe high g (g4). Then they keyboard will just use that sample but "transpose" it when you play a note that wasn't sampled. This is by far the most common method for "real" sounds on cheap keyboards because you don't need as much memory to store the sounds that way -- or you can save that memory for the other features discussed above.