You need to see an advisor in the nursing department at your school, just like you need to go to the nursing department link on your school's website to find information about the program. You can always use the old fashioned method of getting information by sending a letter to the School of Nursing and asking for it. Succinctly, an ASN program is known as a "two year" program, and a BSN program is known as a "four year" program, although both take longer than that. You complete similar prerequisite courses before applying to each nursing program, with more required for the BSN. Some schools
require that all prerequisite courses be complete before requesting admission to the nursing program, while others will allow the applicant to have a course(s) in progress, or allow the student to take certain courses at the same time as they are taking nursing courses.
This is an example of a possible difference: an ASN program requires a one semester chem course for allied health professionals. The BSN program may require a two semester sequence of chem.
Suggest you make an appointment to see a nursing advisor at the schools you are interested in if you can't make heads or tails out of the info on their respective websites.