Board shorts have been around long enough where the line between them and swim trunks or swim shorts is getting blurrier and blurrier. The main points of difference have always been lining—board shorts don't have one, swim trunks do—and length—board shorts are often longer than swim trunks, extending down to the knee. Additionally, while swim trunks typically have an elastic waist, board shorts are fitted, with a lace-up front that provides some size range. Swim trunks also tend to have pockets, while many board shorts do not. All this said, the two labels are pretty interchangeable these days, and features that used to be particular to one can now be found in either.