There are 2 major political parties- the Democrats and the Republicans. The Democrats are viewed by the Republicans as a bunch of "tree-huggin', fag-lovin', hemp-smokin', hippie, yuppie, wiccan satanist pagan, feminist, naive, extremist, radical, liberal crackpots." The Republicans are in turn seen by the Democrats as "racist, homophobic, sexist, foreigner-hating, out of touch, corrupt, biggotted, militaristic, ultra-conservative, fundamentalist Southern Baptist, billionaire oil-barons." So they pretty much disagree on everything.
At least that's my understanding of it all.
Generally, the Democrats hold more liberal states, like California and the Northeast, while the Midwest and the old South are Republican central.
Republicans have a reputation for being corrupt. Their stereotype is the evil old cowboy types you see in American movies; taking bribes and generally being sleazy and money-hungry. They also are known for nepotism. As Jon Stewart, from the Daily Show (A comedy news/talk show type show.) once put it: "Much like the Mafia, Republicans prefer to keep things in the family." Democrats seem to think that Republican beliefs are shortsighted and old fashioned, and destroying the country.
On the other hand, Democrats are thought of as idealistic bleeding hearts, who waste money in endless government programs, and generally are irresponsible with money. Republicans seem to think Democrat policies and beliefs, such as gay rights and gun control (If you can call what they have here control) are destroying the country.
Democrat vs Republican is basically
liberal vs
conservative. For most people, it comes down to whichever presidential
candidate is less of a bad choice.
Clinton's a Democrat, George W Bush is a Republican. You don't have a realistic chance of election to anything in this country unless you're a rich white male. So you can see why so few people bother to vote, being as it's not compulsory.