The first difference:

the data cable is a little thicker than the charging cable because there are four wires in the center of the cable, while the charging cable has only two wires in the center.

The second difference:

there are four iron pieces on the male end of the USB, of which all four need to be connected to the cable, while the charging cable only has two iron pieces that need to be connected to the cable.

Cautions

The difference between a "charging cable" and a "data cable" is that a charging cable cannot transfer data, while a data cable can transfer data.