I wonder if there is a difference in motherboards from two different models of Philips TV's 40PFH5500/88 and 50PUH6400/88. They both have the same Board codes 715G7030-M0G-000-005N. Can I put board from one TV to another regardless of screen size and resolution differences?
The screen size wouldn't be a factor.
It would be odd for a FHD and UHD TV to have the same motherboard. Even if the part and rev numbers were the same there could be a software difference.
If you can find the service manuals for the TVs that might give you some info.