It is a "Humpty Dumpty Word", it means whatever the speaker means it to mean. Nothing more and nothing less.
Thirty and even twenty years ago it was pretty clear -- the anti-communist Jews, mostly former leftists, who were associated with Commentary Magazine and the Public Interest. The neoconservatives were less conservative than the old "real" conservatives such as at the National Review. Often they were moderate to liberal on economics, and on social issues like abortion, and only conservative on foreign policy. On race, they opposed affirmative action but made of a much bigger show of being for civil rights for blacks than did the old-line conservatives.
Today, there is no systematic difference between neoconservatives and real conservatives. One reason for this is that the neoconservative perspective on race has completely triumphed within conservatism. An example: I have seen posts on FR saying that Condi is too liberal to be President, but none saying that she is disqualified due to race or sex.
Ever since 9/11, the term neoconservative has become meaningless, except that the liberals have latched onto the term as an insult.
A more contemporary term for the old neoconservatives might be "metropolitan conservative." A Jewish ex-liberal myself, I LOVED this:
Explanations are just explanations. Look at the issues that divide them.
Neo-cons are world controlling, drag America into war everywhere liberals posing as conservatives to achieve these aims. Conservatives are constitution loving, abortion hating, patriots whose aim is a strong defense and no foreign entantlements.
A dividing issue is Bush's American interest 'road map' for peace. Conservatives think the Neo-cons will be against peace. We'll see.