Typically seamless leggings have one of two different types of stitching sometimes both, they will have whats called internal stitch which basically means the bulk of the stitching is on the inside so it isn't visible to the eye. And then alot of times on most seamless leggings you will have the front seam that goes from the front of the leggings to the back (which sometimes causes the dreaded camel toe), so what manufacturers have learned is they don't use that method anymore instead they put more reinforcement in the inner thigh/gusset stitching to make it so that the front of the legging is smooth and you don't see any visible stitching lines！！！