What is the difference between primary active transport and secondary active transport?

Primary , directly uses metabolic energy (ATP) to transport molecules across a membrane. However, in secondary active transport, also known as coupled transport or co-transport (like simport or antiport), energy is used to transport molecules across a membrane but in secondary active transport, there is no direct coupling of ATP; instead it relies upon the electrochemical potential difference created by pumping ions in and out of the cell (ion gradient).