It is an human instinct.

But I have learned from my experience that the persons do this more are more unhappy in life.

I have the best friend. He's the the best thing ever happened to me.But there are similarities and differences between us.

Similarities

1) We both hate same people

2) We both can do anything for each other

3) We both choose same profession

Differences

1) He is an extrovert and I am an introvert

2) We don't have similar personalities

3) We encourage two different teams

Best Regards Mahesh Kumar

Do you have a particular example in mind? It is possible to find similarities and differences between anything so I don't quite understand your question.

Measuring the self against others is a modus operandi of the human mind, and in some ways, it can be helpful. The inspiration you feel about someone else's achievements can rev up the motivation to improve your own life. The recognition that your abilities are a notch above someone else's can deliver a boost to your self-esteem. But comparisons can be harmful when they leave you feeling chronically inferior or depressed.

It is an human instinct.

But I have learned from my experience that the persons do this more are more unhappy in life.

I don't know about others, but personally I don't compare myself with other people. I am fully satisfied with what I am.

It is human tendency sir, though it is not always justified to draw comparison among various entities/ personalities/ performances/behaviour.

Yes people do comparisons between many things or persons as it is in human nature to do like that. But sometimes the comparison happens between silly things or objects that can can only pity on the person who compares it.