Political liberals speak of "government" when they mean the entity that extracts taxes, makes laws, and enforces them. Conservatives speak of "the state"when they mean the entity that extracts taxes, makes laws, and enforces them. Conservatives also tend to use the term "civil government" for the state. What is the significance of these terms?
Liberals views "the government" as the primary means of ordering common life. It is "the government" that creates opportunities, rights wrongs, and brings about good. Conservatives view the state as one of many spheres of government, including self-government, family government, church government, and more. Most conservatives (of a principled kind) also consider God's government as the final reality. Liberals, however, minimize or deny these other spheres as legitimate areas of order apart from civil government. This is because liberalism is statist: the state is the giver of meaning, order, goodness in the world. All must fall under and be regulated by the state.
Liberalism, in its nature, also tends to be secular. There is no God who exercises His government and who has delegated the various spheres of government: self, family, church, and so on. Therefore, the humanistic state must absorb the functions of all other spheres into itself, baptizing and confirming them according to its autonomous command. "We have no king but Caesar," one might say.
By the way Barack Obama is a political liberal, very far to the left (of the truth).
For more on these themes, see Abraham Kuyper, Lectures on Calvinism; Francis A. Schaeffer, A Christian Manifesto, R.J. Rushdoony, The Politics of Guilt and Pity; William F. Buckley, Up From Liberalism; Herbert Schlossberg, Idols for Destruction; Richard John Neuhaus, The Naked Public Square.