the difference is in the backbone... if the backbone is unsaturated then it is an unsaturated polyester, if the backbone is saturated then it is a saturated polyester...

Saturated triglycerides have more hydrogen's than unsaturated triglycerides.

Fat can be either saturated or unsaturated. It can not be both at the same time. If there is one or more double bonds between carbon atoms, the fat become unsaturated. If all the bonds between carbon atoms are single bonds, the fat becomes saturated.

Chemically, saturated fats have more hydrogen atoms on the fat molecules.

Practically, saturated fats are solid at room temperature (butter, lard, coconut oil) while unsaturated fats are liquid at room temperature (olive and other liquid vegetable oils).

Wax is a saturated fat.