G-string deserve a whole paragraph on their own because so many sub-categories exist! G-strings are similar to thongs in that they offer minimal coverage, perfect for wearing under tighter trousers to eliminate unsightly panty lines but the essential difference is the amount of fabric. In G-strings, a small strip or triangle of fabric covers the front and a string rests between the buttocks (leading G-strings to be coined "butt floss") while thongs have a strip on fabric in the back offering sometimes substantial coverage of the butt crack. G-strings sometimes sport expensive decorations like rhinestones or golden chains. I really think this extravaganza really illuminates the plainness of mens' underwear.
Mens' underwear is mainly bought in packs while women tend to sort through and pick several pairs individually. Most mens' underwear is cotton or a cotton blend. Womens' underwear, however, includes polyester, Lycra, acetate, and other such synthetics. Personally, I'm a 99%-100% cotton fan. But I have nothing against those who chose others. Women love options and maybe that's why there are so many more styles of womens' underwear than mens'.