Ok I got this now.

Right, so apparently there're four, not three, types of fraternities/sororities: social, professional, community and ACADEMIC. My goodness. Honestly, I'm still not one hundred percent clear on the subtle differences between the types but here's what I've made of it so far.

Social: They're here to mingle, socialize, and in general be a huge club with Greek letters; take in all majors but may be picky when it comes to internal standards
Community: Service, a lot of philanthropy which they take seriously; also open to all majors
Academic: Based on GPA and school; get in touch with more academic organizations; more restrictive when it comes to majors but not as much as professional
Professional: usually limited to specific majors; about getting to know the landscape in specific areas

And ALL of them are about getting connections and being part of a group.

via: http://fraternityhq.com/the-4-different-types-of-fraternities/
http://classroom.synonym.com/types-fraternities-4750.html

But besides those four, there're other ways to label a frat, as so Total Frat Movie and its butt munch author "Bacon" has informed me. Their standards for what makes a house "respectable" is exactly why I had wanted to avoid Greek life in the first place.
http://totalfratmove.com/four-types-of-top-tier-fraternities/
http://totalfratmove.com/types-of-bottom-tier-fraternities/
http://theblacksheeponline.com/article/top-10-different-types-of-fraternities

But those aside, I think I'm going to have to get a full copy of Paying for the Party by Armstrong and Hamilton. As helpful random, informal college articles are in helping me get a broad idea of my topic, actual research results would add more security to my stance.

Right, I'm also going to be examining the Rutgers Greek life in particular. It's convenient because it's close to home and I could get interviews from brothers, sisters, and pledges.

RU Greek Homepage: http://getinvolved.rutgers.edu/fraternities-and-sororities

So in simpler terms, my project will revolve around the differences between the four types of fraternities and what influences each of their members to go for that particular house.