Ill ask again, who can post definitive data that cabin wall width and specifically floor height on the 757 vs 737 is different ....
Both the 737 and 757 have an interior cabin width of 11'7" (3.53m) according to Boeing specification.
I cannot quote the floor height relative to the widest part of the cabin as the specification does not quote this.
Edit:
Cabin height B737-800 - 2.2m
Cabin height B757-200 - 2.13m
Sorce - Flight Global