There are many differences between a republican and democrat. A republican is usually pro family, pro religion, pro military and pro big government. Republicans are usually anti abortion, anti gay rights, and anti helping with federal or state money for the poor.
Democrats are pro choice, pro smaller government, pro gay rights and pro freedom of religion. Democrats are against outlawing abortion. Democrats are for the federal government and state to help with the poor and social service programs.
Democrats and Republicans views vary widely but there is always some cross over between the two political parties depending on the person. The best way to know is to research the candidates beliefs. More info: difference between republican and democrat