Changes from Beta

Hey everyone, I just started to play some of the single player campaign and it looked like there were some differences from the beta which I stopped playing about 2.5 months ago.. For instance I noticed there were medics which weren't in the beta. Did SC2 make a lot of changes from the beta? If someone could give me a quick rundown of the major changes in the past few months, I'd appreciate it. Thanks

There are loads of things in single player that arent available in multi. Multi is unchanged from beta