Comparison between similar things
Incorrect: His pen is better than me.
Correct : His pen is better than mine.
Note: In the first sentence here, his pen is compared with me as a person. Such a comparison is absurd. A pen can be compared with another pen. In the second sentence "mine' means 'my pen'.
Similarly:
Incorrect : The mangoes of Alan are better than Selena.
Correct : The mangoes of Alan are better than those of Selena.
