The only difference that I could see (and this is just my opinion) is that generally summer research is a full-time 40+ hour work week where you just won't have the time to do that during the academic year so it would be seen as a more intense experience. But, again, that's just only my opinion.
um, I'm pretty sure that research is research. Like shantster said, you might work more hours at one than the other, so that would be a factor, I guess. The point of research though is not "I spent more hours than you," so don't get hung up on that.
research is research. i did two summers of research and as of last semester started doing research during the school year. doing summer work is so much easier because there are just less things vying for your time. just remember that if you want to line up a position for next summer, start getting your package together and get your letter ready. the applications usually start around the new year.
Actually, it depends on what kind of summer research you did. There are summer undergraduate research programs offered at many schools and are highly competitive. Usually they pay you a stipend. You are assigned to a project with a grad student or a PI and you get to learn a lot of hands-on stuff. (Sometimes if you are really ambitious you can make up your own project) Then, at the end of the summer you present your results to the department faculty and staff. Thus, it looks favorable to have completed one of these programs..
When it comes to just doing full-time research during the summer.. that is more or less just research because its not associated with a competitive program.
So, if you have the chance to do one of these summer undergrad research fellowships/programs I would recommend it.. It looks good on apps and has personally helped me a lot when applying for grants and other awards