They are all part of the violin family, the full name of a cello is the violoncello.

Instrument names in the violin family are all derived from the root viola, which is a derivative of the Medieval Latin word vitula (meaning “stringed instrument”). A violin is a “little viola”, a violone is a “big viola” or a bass violin, and a violoncello (often abbreviated cello) is a “small violone” (or literally, a “small big viola”)

The names were derived the same way as your title basically lol