Can someone tell me what the difference between a Ba and a BSc degree is?
BA = Bachelor of Arts
BSc = Bachelor of Sciences
Generally, you get a BA if you study an arts subject, and a BSc for a science subject, simple as that!
There are some exceptions (all Cambridge degrees are BA, for example), and some subjects could fit into either, in which case the uni will have some criteria to assign what the degree is. This doesn't actually matter though - both qualifications are at the same level.
Some universities offer what appears to be the same course twice, one as a BA and the other as a BSc. In these cases, the BSc courses tend to have higher maths and science content than the BA version.
And again, in some cases they don't differ at all and it's merely cosmetic. Basically, if you have a choice, you'll have to check what the individual circumstances are for each.
One is more sciency than the other. And one is more arty than the other.