<p>Congratulations! These are both fabulous schools, and you have a wonderful choice. Try to spend time at both (preferably outside of their admitted student week-ends when things are more typical). The right answer for you should become much clearer. The schools' sizes, campuses, surrounding communities, and weather are obvious differences. The schools' cultures and "feel" are also quite different. Here are some random thoughts after visiting both places several times with my son, and after hearing him discuss his visits. (caveat - the visits were short, and I'm not a student. Others may give you more informed impressions)</p>
<p>Caltech, perhaps because of its smaller size, seems more academically focused than MIT. If you are oriented towards research and already have a clear idea of your interests, Caltech might be better. Research and academic focus are available at MIT also, of course. But if you view college as a time to try lots of different things, MIT would give you a broader range of classes and activities to sample.</p>
<p>I don't honestly believe that students at either school are significantly more or less happy or stressed or overworked than at the other. But there seems to be more of a "united in adversity" culture at Caltech. Caltech students are more likely to say "don't go here", "it's too hard", etc. I think it's sort of a Marine mentality, like saying it's only for The Few, The Proud, and mere mortals shouldn't attempt it. MIT students are more likely to say that it's fun and they are having a blast, and to encourage prospective frehmen to attend. </p>
<p>I think the top students are similarly brilliant and hard-working at both schools. There is probably more of a difference in the bottom students. If someone who was not brilliant and hardworking found themselves at one of these schools and just wanted to squeak by, I think that would be much easier to do at MIT than at Caltech. If you got there and decided that you aren't really as passionate or talented as you thought you were in nuclear physics or complexity theory or whatever else you thought you were going to devote your life to, you would have more options at MIT. At Caltech, you might have to transfer out.</p>
<p>The MIT campus has more people on it per sq. inch, particularly when the weather is bad and everyone is inside. This increases the urban feel and sense of energy. Caltech has a gorgeous campus, with much more use of outdoor space and a greater feeling of serenity.</p>
<p>At Caltech, student social life seems centered on the houses which operate sort of like a cross btwn dorms and fraternities. There are not a lot of places outside the houses where students seem to congregate and you don't see a lot of students in common areas. Undergrad houses are close to the classroom buildings, which may encourage people to go back to their house if they have some time off btwn classes. At MIT, people are loyal to their dorms/halls, but also seem more likely to form groups based on interests. Some of the dorms are too far from the classroom buildings to reasonably go back to your room during breaks btwn classes, and there seem to be more people hanging out in public areas.</p>