In Starfleet, both science and medical personnel wear the blue-tinted Sciences uniform.
More broadly, all science is defined as belonging to either the the natural sciences (physics, geology, exobiology, etc), or the "human" sciences (anthropology, archaeology, economics, linguistics, etc).
I think Star Trek Online (the MMO game) puts it pretty well. They imply that generally each section (engineering, tactical, science) has two divisions that extremely vaguely put could be the section split into Ground and Space divisions.
Science' is pretty mixed between space and ground, and has Medical (more Ground based, although obviously people injured get taken to sickbay, you get more ground injuries than space injuries usually). The other division is just called Science I believe. Science generally [not always] is more involved with space.
Tactical has Security (more Ground based, make sure you take a lot of red-shirt security officers down with you on away missions, but also keep them on the ship) and Tactical is more space based with Starship weapons etc.
Engineering is split into Operations and Engineering. Basically the same thing as I said before, one more ship based and the other more ground based.