I'll attempt to be as neutral as possible and give both parties the benefit of the doubt.

Democrats represent a technocratic centralized authority with liberal egalitarian economic values and loose social norms. Their main concern is Fairness and Equality. You might find them equal to the British Tory. Democrats believe in central government and running programs through the federal system.

Democrats are a big tent party who represent everyone from social liberals who don't care much about economic concerns, to socialists, to regular people who feel Democrats run things better but aren't sure why. This big tent nature leads them to be fractured and easily routed when they have equal numbers. A super majority is not a super majority due to the diversity of views. Many mainstream liberals mistake this for cowardice when in fact it is infighting

Republicans are another big tent but are more united in their beliefs, particularly since the Tea Party movement. Republicans can vary as Socially Liberal Fiscally Conservative Libertarians, to the Religious Right. Republicans are concerned with Liberty (in the sense of individual economic freedoms) Tradition, and Economic Growth. They believe freer markets lead to greater growth but most are not approving of removing every regulation as they are often charged with. Republicans are disapproving of federal intervention in economic matters, preferring states to decide. When it comes down to legislation Republicans stop infighting and put up a united front. This is seen in the shrinking of government in the Clinton Administration and the growth of government in the Bush years. When you talk to the Tea Party you hear how unhappy they were in the Bush years but that they didn't protest because he was 'their guy.' Their deference to authority is evoked even when it goes against their goals. Their social goals include maintenance of tradition with only gradual social change. This makes them mortal enemies with social liberals who see themselves of freeing victims from brutal authority and bigotry. Republicans see themselves as vanguards of a noble tradition under attack. You can draw your own conclusions about reality, but I believe this is more or less an accurate view of perception.

It should be noted that there will be some misdirection about whether we really have two parties. We do. The misdirection comes from being too far on either side of the political spectrum. Rothbarian Anarcho Capitalist will call any government with an income tax socialist. And Noam Chomsky will call any government with a large corporation inside it's boarders a corporatist nanny state. These are exaggerations but they are illustrative of the point that if you are too far to either side it is harder to see the difference between the two parties. When you contrast their stated goals they seem quite apart.

I will not address lobbying corruption and the like. It is quite bad here, not nearly as bad as many countries, but it is a problem. The reason I will not address this is that language becomes tilted and blames one industry or side without due evidence.