Ah. The pinheads arrive. You're about two posts behind schedule, but I'll assume that you hit traffic. No great loss.
The difference is, old-school conservatism tended to accept the results of scientific inquiry, but argued over whether the benefits exceeded the costs. For example, "Is saving the spotted owl really worth shutting down the Oregon timber industry?"
Neoconservatism simply rejects the results of scientific inquiry outright. "There is no spotted owl. There never was any such animal as the spotted owl."
There may be a legitimate reason to believe that the costs of addressing global warming will exceed the benefits. (IF there is, I've never seen one -- but it's not outside of the realm of possibility.) There is no legitimate, or even reality-based, reason to deny that anthropogenic global warning exists and will result in major climatic changes in the moderate-term future.