what is the difference?
The GOP is in the business of having more GOPers elected.
Conservatives are in favor of protecting rights by strict interpretation of Constitutional law and promoting individual responsibility rather than government dependence.
Recent examples of differences include:
1. Campaign Finance Reform - This was favored by the media, so the GOP pushed for it (lead by McCain, signed into law by Bush). There are provisions in this act that clearly prevent free speech, and the act is proving to have little effect on finance abuses anyway - conservatives are heavily against this and it is a major point of difference between McCain and Conservatives.
2. Prescription Drug Subsidy - Again, as issue heavily favored by the media, so the GOP and Bush pushed for its passage. This is a very costly program, requiring an unfair proportion of earnings confiscation from wage earners, and further promotes dependence on government programs. It also interferes with the market forces which makes capitalism so successful.
3. Dragging Feet on Border Security - Despite being legally required to build a border fence, Bush and the GOP (and the democrats) are making little effort to complete the project. This is because both parties believe that the Latino vote will carry a lot of weight in the near future and neither party wants to tick them off. Conservatives believe that national security is one of the main Constitutional functions of government and that Bush/Congress are not performing their Constitutional duty in this regard.
There are other areas where conservatives and the GOP differ (Farm subsidies, Education, environment, United Nations, etc)