Ok, I'll bite. Curiosity without resolution is a tease. Which filter on which picture? And why?
The upper shot is FP4+ with no filter.
The second shot is FP4+ with a red filter.
I was concerned at the time of exposure of the risk of tonal merges of the masonry and the sky.
So I grabbed the red filter. Any fear of tonal merges disappeared in a flash.
BUT ...... My aim is not to make 'pretty pictures' but to be more documentary — something which the 'no filter' shot accomplishes. The red filter is a bit too 'photographic' for my taste. However, people top whom I have shown printed of this have all opted for the red filter version. (Somewhat to my documentarian chagrin!)
Cheers, and thanks for asking.
PS: Maybe I'll reach for the reliable old Yellow/Green or Yellow next time.