What is the purpose of 4 years college and 2 years colleges

It depends what your Masters is. If you want something in the medical field, you are bound to stay in college longer. It also depends how much you are willing to pursue your education.

I feel that this question is vague. I will answer it to the best of my ability's.

A four year college allows you to receive a bachelor degree, which ill allow you to receive a higher paying job while a two year college only give you an associates degree. With this degree you make lees and there are less jobs. The best thing I can ecomend is to start at a two year college then transfer your hours.