whats the difference

:)

Usually cost.

Formal programs also have more application processes and GPA cutoffs (usually around 3.0). Some programs are up to 3 years in length and are full-time with mandatory volunteer time. Most are 2 years. Many are upwards of 30K/year. Some have official or unofficial linkage programs-- you need to ask how many still apply today as they are being phased out.

Informal programs usually mean that you sign up at a local college and bang out the requirements for med school. There may or may not be a premed advisor or committee. They are most flexible for working students (unless you live in NYC or another major city and many of the 4 year schools have evening classes) and can take longer.

Then there is the hybrid, very special program like what I had at City College of New York. It is a formal post-bac in that there is an application process and a premed committee. However, they are used to having a lot of older non-trads and the school has a lot of night classes, perfect for those of us who were working while doing the reqs.

Here's a link (http://forums.studentdoctor.net/showthread.php?t=114425) to the post-bacc FAQ in the post-bacc forum. Hope that helps! Any other questions you have about the topic will probably be better answered there.