Democrats are generally more liberal. They believe in a larger federal government, and often implement tax plans to try to help the less privileged. They tend to believe the government must look for the greater good above the individual person in terms of welfare and do what is necessary to make the populace more "equal". They assert that the values our country holds must evolve over time, and, therefore, tend to support such controversial choices as Pro Choice and gay marriage.
Republicans are generally more conservative. They believe that the answers do not lay with the government generally, but rather with the people. They want less government interference and tend to believe more strongly in property rights and less strongly in well-fare rights, holding economic equity above equality. Many republicans are religious and tend to hold to the morals characterizing the Founding Fathers, which results in general disapproval of abortions and, for some, gay marriage. To sum it up, Democrats lean toward equality under a large federal government. Republicans lean towards people looking after themselves and their neighbors under small federal government and strong state governments.
There is really one difference. Republicans do not feel that government is bigger then the people that it serves. Dems feel that government is to supply the needs of all the people it governs. The two parts have switched believes over the years.
I'll put it to you like this..... If you're not a democrat by time you're 21 then you have no heart. If you're not a republican by time your 30 , you have no brains. It's an old saying and can help u to remember how to distinguish the 2 apart.