"Handpan" is a generic term for instruments that were inspired by the Hang and use the same principles. As the name implies, handpans are meant to be played with hands. Beaters are not recommended, since they might damage the instrument or detune it.
The word was coined by Pantheon Steel, who were among the first makers to produce their own version of the Hang. Sometimes, handpans are also called "pantams", or improperly, "hang drums".
It's important to note that steel tongue drums can also be played with hands, and that the bigger ones can look and sound like handpans, so the frontier between both is sometimes thin.
Instruments such as the RAV Vast or the YW Pulsar, while using slit metal "tongues", are good examples of this kind of hybrid design. Some websites even categorize steel tongue drums as handpans, which can cause quite a bit of confusion. Telling the two apart is simple: handpans have no tongues.
While large, high-quality steel tongue drums usually stay under the one thousand dollars mark, handpans are way more expensive and easily reach at least twice this price. They're harder to build and tune, require finer materials, and are also more fragile.
Hint: don't call handpans "hang drums", or PANArt may sue you. I don't know if they ever threatened Hang Massive, but I hope they won't, as these two make fantastic music.