Both IHM Mumbai and IHM Pusa are reputed institutes for hotel management. The comparison between these two institutes seems to have no end. No matter which institute you join, you will learn to love it. Both offer decent academics. India Today ranked IHM Pusa and IHM Mumbai 1st and 3rd for Hotel Management respectively. 

When you are choosing one of these two make sure you consider the factors like hostel, city, food, distance from your home. Talk to the current students and go for the culture that attracts you more.