bhp is measured on an engine dyno basically
with your transmission on, thats what is now called SAE NET HP
used to be SAE Gross HP, which would be with all of your accessories driven by an outside source
now it is SAE NET HP
so yes, bhp is going to be a little more than whp. since it is reading at the flywheel/transmission input shaft rather than at the wheel
most tuners are going to want to tune your car on a rolling dyno, not an engine dyno