I had taken some measurements earlier for these two axles, but today I decided to measure the circumferences of them to get a more precise measurement.
Eaton:
Circumference imperial & metric units =
10-5/8" & 26.85cm
Corporate 14Bolt FullFloater:
Circumference imperial & metric units =
10-3/4" & 27.20cm
..
So, the 14Bolt ff has a circumference of 3.5mm larger than the Eaton.
This translates to less than 3/64" difference in Diameter.