Arch Support generally refers to the part of the insole of the shoe that raises right at the level of the arch to provide support to the midfoot. Arch Support also refers to individual insole cups with a molded shape that fit the arch and are placed inside the shoe to help relieve foot or heel pain.
About Strappy Sandals:
Strappy Sandals are sandals that are characterized by multiple straps covering the toe and/or heel. The straps on Strappy Sandals can be used to secure the shoe to the foot or some of them may be more for ornamentation.