Both conservatives and liberals are, in their own mind, strongly patriotic and have the best interests of the nation at heart. Both believe strongly the in the principles espoused in the United States Constitution and are committed to preserving those principles. They disagree as to the interpretation of those principles, and the extent to which power should be shared between the Federal Government and the States. No stronger statement of the political similarities of the two groups can be had than when members of Congress from both parties stood on the steps of the Capital on September 11, 2001 and sang together, "God Bless America."
The answer to this depends to some extent on the country that you are talking about. In the United States, the two ideologies share a great deal in common.
For example, in the US, both conservatives and liberals are strongly committed to the ideas that are embodied in the Constitution. Both ideologies are strongly committed to having a fully participatory democracy with universal suffrage. Both ideologies believe in a limited government (though they don't always agree on where the limits are) and in separation of powers. Both believe in equal rights for all Americans (though, once again, they differ on details). Both believe in capitalism and in individual responsibility.
In the United States, at least, conservatives and liberals are both fairly centrist. They are strongly committed to similar principles even if they do have important disagreements about the exact details of how these principles should be put into action.