The major ideological difference between liberals and conservatives is that liberals favor expanded government intervention in peoples' affair while conservatives tend to want to limit it. Liberals believe that bigger government better protects aspects of equal opportunity, human rights concerns and civil liberties. Conservatives believe government should exist only as far as to protect basic freedoms.
Regarding limited government, conservatives desire a state that can provide for basic liberties and common defense, but that otherwise leaves the majority of decisions to state, local and individual initiative. By extension, conservatives tend to favor free markets, little to no government regulatory intervention and an overall approach that trusts individuals and their innovations to solve social problems. One example regards health care approaches, with conservatives favoring the independent action of market forces, and liberals favoring government promises of benefits for all persons, regardless of income or pre-existing conditions.
With respect to social issues, liberals tend to be supportive of expanded energy sourcing, affirmative action in education, stem-cell research, physician-assisted suicide and expanded gun control legislation. Alternatively, conservatives generally combat any threat to a wide interpretation of the 2nd Amendment, and support traditional Christian interpretations that would ban abortion, stem-cell research, euthanasia and same-sex marriage. Regarding immigration, conservatives typically reject offering legitimate status to anyone who has come illegally, while liberals often favor some degree of amnesty.