Fresh beans are sweeter on the palate. They also have a "fresher" quality to them. The best example of this is the difference between a fresh pea dish and a split pea soup. Both can be delicious but the fresh pea dish might be sweeter and have a more floral, aromatic quality to them.
Dried beans can slightly more grainy, but this can be mitigated via cooking methods.
Because the fresh beans are more tender, they cook much quicker than dried beans. Roughly 20 to 30 minutes versus the 1-3 hours for dried beans.
The skin of fresh beans are both tender and sturdier than dried beans. They hold up better when cooking so typical bean-issues like burst and broken skins are much less of an issue. The fresh beans hold up to early salting, turbulent boiling water, and vigorous stirring because of the strength of the skin.
I couldn't find much research on the topic other than how many nutrients dried beans retain rather than lose. The general consensus seems to be that dried beans retain much of their nutritional value.
Much of the water-soluble nutrients of beans can leak out during the soaking and cooking process but provided that one also consumes those liquids it's easy to enjoy the benefits.