Looking at a Chiltons manual and it shows "Net" Horsepower for a certain engine under the I.D. Section being 185.

But then when you look up the same motor in the same book,under the specifications section,it shows Horsepower to be 210.

So whats up with that?

Is one "Gross" and the other "Net" and what do each mean?

Net is after the accessory losses, so it is less(alt, ps, wp, etc. )

gross is at the flywhell

net is after the accessory are added,and the a/c is on,IIRC unless its a non a/c engine

#s do vary from book to book also..

Gross and Net are both measured at the flywheel. Gross is just the bare engine, net is the engine plug the water pump, alternator, power steering, etc hooked up. Also keep in mind the year they changed the ratings systems over is also the years they started dropping compression ratios so you can't always compare one to another.

Another possibility is that the factory has 2 different numbers in their data. It happens all the time.
One more possibility is that it changed from the year before, and they changed one and not the other.