Tuscany has an outlet mall at it's back gate (literally, there's a gate), a grocery across the street (Publix), and some nice (chain) restaurants close by. Its more convenient to Disney, and seems a bit more adult-oriented.
SeaWorld, OTOH, seems more family-oriented and tucked away from the world on a larger campus. It's closer to Universal and there's a free shuttle to SeaWorld (the park). Its older - it and Flamingo were the first HGVC resorts - but recently updated.
Both are very well maintained and meet HGVC's high quality standards. SeaWorld is my home resort, but when we go to Orlando, we usually alternate just to get a different ambiance.
You can read reviews here on TUG or Trip Advisor.
.