Hi,
There's no universal definition for the difference between a BA and a BS (ie: it's college dependent) but generally the difference is that the core requirements of a BA program are generally more liberal arts and humanities based whereas in a BS, the requirements are more science based. For example, at UPenn, the BA comes under the College of Arts and Sciences and has those requirements in the core whereas the BS is in the school of engineering and the core has more technical requirements.
In terms of employment, if your school only offers a BA degree, I don't think it'll be held against you. There are a lot more factors that go into deciding employment than the type of degree you have (GPA, internships, activities etc). In terms of masters, I think it depends upon the course you're applying for, and you'd be able to find that out by checking the specific requirements. However, I don't think it should be detrimental to you unless you're applying for something highly specialized or technical.