yes, most jobs will pay more for a bachelor's degree rather than an associate's. just like in most positions- the more education you have, the more likely you are to be paid a higher salary.
however, most jobs in preschool look for someone with experience. to become a preschool teacher in the state of california, you will only need 12 core units of early childhood education (4 classes). my advice would be to get the experience FIRST. most jobs will be looking to see if you are passionate about teaching young children, and not just looking to work with kids. once you get the experience down, then worry about completing a BA or AA. just my advice. it isn't necessary to complete either of those degrees, however, if you are looking to go into teaching. it really just depends on what your ultimate career goal is in childcare. if you want to become a director of a childcare facility, you will need a BA and most likely some years teaching experience.