What is the difference between these two products?

I have been separated from her for a year.

Please tell me the difference between these two products.

I will return home.

He returned home.

They walked down separate paths.

I think we should try a different method.

Oil is an important element of the world economy.

He is an expert in petrochemistry.

On a cold winter night, a kerosene heater is indispensable.