For anyone except the experts, a 5-string banjo is stuck in a few keys: G, C, and some chancy minors. That’s mostly because of the standard tunings, but partly because of that G 5th string. If you want to play in another key, you need to capo up the fingerboard.
With a standard 5-string banjo, capo, and separate 5th string capo, you can capo up to the 4th fret. After that, it gets weird. With a capo-ble banjo, you just clamp the one capo on, at any fret. You can adjust to your singing range, or to the preferred key of your group.
Of course, with either banjo you can use a nonstandard tuning, retuning a minimum of 2 strings. You’ll have to relearn where the notes are. Then, of course, your group will decide that they like another key better!