I'm trying to validate some hand calculations of heat transfer coefficient with turbulent flow through a pipe wall. I've setup a simple flow model with said pipe/flow (internal flow, adiabatic out wall) & measure the surface properties on the inner wall of the pipe.

When selecting criteria I'm given two options -- adiabatic HTC & (non-adiabatic) HTC. I've run a few differnt simulations with differing boundary conditions & all of my hand calculation (excel-driven) values match for adiabatic HTC. The (non-adiabatic) HTC values are always lower. The only literature I've been able to dig up online is below (sorry for the bad crop, source was like this):

So my question is: what is the difference between the two?

Thanks.