Thank you for posting @slowwalker, nim this historial article and interesting artistic photographs.
Thank you for opportunity to think on these things.
As a result of studying the photographs of the pieces of roof end tiles.....a couple of very small differences.... may be the colour preference of the two time periods as the Baek Je favours the darker.....and the difference in the attention to detail being stronger in the Shilla.....perhaps.
Looking forward to hearing what your friend had to say.
Wishing you and your family all the best.
Cheers.
In my opinion, colors were not so different each other.
The tiles were made in the furnace both Baek je and shilla.
I will ask my friend
Thank you