Superior + to
Incorrect : This book is superior than that.
Correct : This book is superior to that.
Note: Although two books are compared here, the adjective "superior” is not followed by “than”. It is always followed by “to”. Like “superior”, “inferior”, “senior” and "junior” are also followed by “to”.
For example:
These mangoes are inferior to those mangoes.
He is senior/junior to me by two years.