I can’t really give a thing for either party as a whole…
Republicans are composed of Libertarians, Neocons, Values Voters, and Paleocons
Libertarians are more or less anti-government, and generally want a smaller, leaner government (true anarchists, as arule, do not vote and do not vote Republican). They get really pissed off at
Neocons have relatively little interest in business or economic issues. They are in fact leftists but crossed over because the Democrats started going into the deep-leftism (as exemplified by McGovern, etc.) They tend to be liberal on domestic issues but desire an aggressive foreign policy, seeing this as the only way to safeguard both America and prevent tyrannies. They see the world as a violent and chaotic place that is not particularly advancing.
Values Voters as a discrete group started popping up alngside the Neocons, and the two groups do not get along. VV’s want a more traditional social order, tend to be protestant/evangelical, but generally want to stop things like Gay Marriage than start something themselves. They tend to think of government and religion as a partnership in common goals, and despise the arbitrary (at least as they see) and not-at-all-Constitutional idea of “wall of seperation between Church and State.”*
*I qualify the word “arbitrary” and not the latter because they are right about that. It’s not Constitutional and was another of the we’re-making-stuff-up disco-era judicial creations. That’s a matter of fact, although what is right is not something I’m prepared to talk about here.
Paleocons tend to be strongly anti-Communist and pro-business. This is usually Big Business, but they generall don’t much care. They would argue that in the long run, or even relatively short run, workers are better served by healthy and efficient businesses and their own ability to leave rather than attempting to control everything.
Republicans as a whole share certain attributes: the ideas of John Adams with regards to government, a no-nonsense Jacksonian attitudes toward following the rules, and a Theodore-Rooseveltian Walk-Softly-and-Carry-a-Big-Stick foreign policy stance. They favor free trade as a general rule, and want to ally with countries like Columbia. Note that the shared themes are fairly strong, more or less. Any given Republican can probably identify with two, if not more, of the above.
Democrats tend to be a bit more ideologically diverse. They include
Academics - Professional scholars in American tend to be very leftist.
Communists - Not too many left. But they exist and are very active protesters.
Great Society Junkies - they favor a strong welfare state and subsidies.
Environmentalists - everything from Anti-Nukers to Hair-Shirts to Sierra Club Members.
Animal Rights Activists - they overlap with environmentalists some but not entirely.
Progressives - these shade from pro-regulation (want more safety rules) and overlap with environmentalists and so forth.
Big City Machines - New York, Chicago, IIRC Detroit and Saint Louis, and many other cities all have serious machines running which control virtually everything, politically. Their power has waned over the years in most areas. There are Republican Machines here and there, but not nearly so many.
Racial groups - mostly includes Blacks. “Asians” and “Hispanics” are less predictable, and both are hugely varied groups anyway.
Yellow Dog Democrats - these are conservative, and might otherwise be Republicans, but come from historically Democrat areas, so it’s tradition. Or something. Their votes are unpredictable, and they often serve as the swing vote in Congress.
Last but not least, the totally random activists - there’s a nontrivial chance that in any given decade some weird issues arises that somebody protests continually.