They were very close ideologically speaking which is paradoxical
Despite running for opposite parties (the Democratic Party for Gore and the Republican Party for Bush) they had little ideological opposition just like Kennedy and Nixon in 1960. Bush ran on a "compassionate conservatism " platform and Gore was the heir of President Bill Clinton (of whom he was Vice President) who had governed on a third way stance (less government intervention than what liberals generally advocate.)
They were thus very moderate in their own camps and close to the centre politically speaking. They both agreed on climate change(though bush slightly changed his position during his presidency) but they differed on foreign policy. Gore had been an adovocate of war in Somalia and Yugoslavia, Bush criticized this position and called for more isolationism(which is a return to the Old Right tradition). Nonetheless he gave up those promises after 9/11.