Hello Manjusha,

A non-inferiority trial aims to demonstrate that the new drug is not worse than the comparator by more than a small pre-specified amount which is called the non-inferiority margin. In other words, the new drug is at least as good as the comparator and not worse.

A superiority trial aims at showing that the new drug is superior (better than) the comparator.

An equivalence trial is commonly designed to confirm that the new drug is similar in efficacy to the comparator. Such a trial aims to show that the new drug is no better and not worse than the comparator.

Best.