Here is a primer Nilsen...
The prevailing thought is:
Liberal = Democrat, Conservative = Republican although there are shades of gray throughout the political theory and each issue is different for each individual. There are conservative, liberals, and moderates in each party.
Two parties dominate, Demos and Repubs, but the Green, Libertarian, Reform, and a myriad of other parties exist. We even have a Communist party.
One basic theory of what differentiates liberal thought from conservative is the role of government.
Generally, as far as the primary drivers of the social structure, the liberal view has a larger role for government than the conservatives like and the conservatives have a larger role for private enterprise than the liberals favor.
The conservatives tend to favor a greater role for church and tradition as restrictions on behavior of citizenry, where the liberals tend to favor a more lassie-faire approach to personal behavior and responsibility.