What are the differences between relative concepts and absolute concepts?

*Absolute: free from imperfection; complete; perfect.

* Relative to be compared to something else

If you get what i mean, like

"einstein's_theory_of_relativity:" Definition for einstein's theory of relativity:relativity: (physics) the theory that space and time are relative concepts rather than absolute concepts.

Relative means it can be compared to something else like this case its not unique, but to be Absolute it is unique and it has no comparison.