Political parties have the same aims and similar forms, but are different in many ways. Each party must pass through the filter of political reality, as in the mode by which internal politics is conducted. The difference is not one of politics, but of political culture.
Political culture is defined by the INTERNATIONAL ENCYCLOPEDIA OF THE SOCIAL SCIENCE as: ..
the set of attitudes, beliefs, and sentiments which give order and meaning to a political process and which provide the underlying assumptions and rules that govern behavior in the political system. It encompasses both the political ideals and operating norms of a polity. Political culture is thus the manifestation in aggregate form of the psychological and subjective dimensions of politics. A political culture is the product of both the collective history of a political system and the life histories of the members of the system and thus it is rooted equally in public events and private experience. While there are many fundamental differences between the democrats and republicans, the most fundamental difference in which all others are rooted is structural:
In the Democratic Party, power flows upward and in the Republican Party power flows downward.
The second is attitudinal: republicans perceive themselves as insiders even when they are out of power and Democrats perceive themselves as outsiders even when they are in power. The democratic party is composed of constituencies. These constituencies identify themselves as having a common agenda which the party must respond to. They are recognized by party officials as representing the interest of important blocs of voters. Some have been recognized since the New Deal while others are relatively new.
In 1983 there were seven such caucuses, five representing demographic groups (Women, Black, Hispanics, Asians, and Gays) and two ideational ones (liberals and business people). The republican party also has relevant components, but they are not as important as the democratic party’s group because they are not mechanisms for exercising power and are not primary reference groups. The basic components of the republican party are geographic units and ideological factions. The entities exist only as internal party mechanisms.
The geographic units consists of State and Local parties and are primarily channels for mobilizing support and distribution information on what the party leaders want. They are not separate and distinct levels of operation. Unlike democratic caucus leaders, republicans faction leaders do not feel themselves accountable to their followers. That is why the republican party has been slow to reflect changes in the American population.
If you would like more information regarding the two parties please read, “The Political Culture of the Democratic and Republican Parties,” published in the Political Science Quarterly.