Iām only familiar with 5-string bluegrass banjo. Two big differences: itās tuned to an open chord, and the drone 5th string changes everything. When I learned to play guitar, almost immediately I fingerpicked in a three-finger Scruggs style (and still do). Forward rolls, backward rolls, hammer-ons, pull offs, etc. Essentially the basics of bluegrass banjo, done on the guitar. However Iāve never read music or understood theory, and for some reason I could never comfortably transition to the banjo, even after a few years of lessons. I could memorize tunes just fine, but for some reason I couldnāt intuitively be creative on the banjo. It simply wasnāt rewarding from a creative standpoint & I finally gave it up. For whatever reasons, I find the mandolin to be more intuitive & much more satisfying.
A quality banjo will be comprised of a multiply maple rim & brass tone ring, but of course the good stuff isnāt cheap. Iād recommend staying low buck in order to get your feet wet, and then decide whether you want to jump into the deep end. Good luck - and may the force be with you!