How is Polypropylene different from Polyethylene?

Here is a list of some of the differences between polyethylene and polypropylene: 

Polyethylene and Polypropylene are very similar as far as physical properties.

However, Polyethylene can be produced optically clear where polypropylene can only be made translucent like a milk jug.

Polyethylene does have physical properties that allow it to stand up better in cold temperatures, particularly when using it as signs.

Polyethylene is a good electrical insulator. It offers good tracking resistance, however, it becomes easily electrostatically charged (which can be reduced by additions of graphite, carbon black or antistatic agents).

Polypropylenes are light in weight. They have a high resistance to cracking, acids, organic solvents and electrolytes. They also have high melting point and good dielectric properties and are non-toxic.

Monomer of polyethylene is ethylene and monomer of polypropylene is propylene.

Polyethylene has a lower melting point compared to the higher melting point of polypropylene. (this may be a good test for you)

Polypropylene is not as sturdy as polyethylene.

Polypropylene is stiffer and resistant to chemicals and organic solvents compared to polyethylene.