G-string and a Thong are very similar in design and this may cause some confusion in identifying these panty styles. They both expose your buttocks and they have a very similar cut. The idea of these two styles is not to look exposed but to minimize the panty lines when something is worn on top of them. Once you know the difference between them you will never mix the two again.
G-string has a string going around your waist and down between your buttocks. The string is very thin so that when worn with a tight dress the string does not show through. It is a very simple design but very functional. The front of g-strings is sometimes made of sheer fabric in a triangle shape to provide coverage for the most important private parts. When the g-string design and term came out it created a mixed reviews. The main thing was that unfortunately people did not understand the purpose of a g-string and they perceived this style to be a sexual and designed for the women that are bit on a exhibitionist side. As times changed the practical meaning of these panties is coming to life.
Similarly to a g-string, a thong is a fabric based panty style. It has similar practical qualities of minimizing the panty lines with two distinct differences. Thongs don't have strings. Thongs have thin lace or other thin fabric that goes around the waist and in between the buttocks. The area in the back that connects the horizontal line with the vertical one usually is in a "Y" shape where a g-string creates a "T". Those are the main distinctions between these two types of underwear. Thongs can be more comforting and pretty because they have more fabric wrapping around your waist and down your but. Thongs do give a nice effect when the fabric is of high quality like French lace or super fine silk. But from practical point of view g-string is better at masking the panty lines under a dress or tight pants. Both styles can be found in beautiful designs. If you have no other alternatives of concealing your panty lines now you are educated on the topic and the decision is up to you. Some women just plainly like it from the design point and more power to them. Enjoy what you are wearing because the most important thing is what you like and feel comfortable with.