For the first two years of your college life, you may regret not joining IEM, in the last two years this will not matter much. 

• IEM is also quite strict. According to my friends at the institute, you are not allowed to use cell phones inside classrooms. If a student is absent for two consecutive days, then his/her parents (or guardians) are called for inquiry purposes. The same situation would arise if you do not secure good marks in your examinations. 
• According to my IEM friends, the teacher-student interaction is not as open and there is an unspoken barrier between them. HIT, on the other hand, has helpful teachers in these areas. If you have any questions, you can contact them at any moment, including over the phone. Teachers in HIT also assist you in developing your research interests. They will motivate you to study even for topics that are not included in the curriculum but are relevant to it. 
• IEM is unquestionably better than HIT when it comes to campus placements as per the records of the past few years. Many students get the opportunity to appear for the recruitment process of core companies. According to the recent placement highlights the highest CTC offered at HIT and IEM were 16 LPA and 72 LPA respectively. 

However, whether you select CSE or IT, I recommend that you go for HIT because the placement percent is the same in both institutions for IT-related streams, but the faculty of CSE and IT at HIT will provide you with better support and encouragement.