Well I don't know !
Let's get together and look into it.
The radius of the sphere and the side of the cube have
the same length. Let's call that length ' L ' .
The volume of the cube is ( L³ ) .
The volume of the sphere is (4/3) (pi) (L³) .
Taking several minutes to examine those quantities carefully,
I noticed that
( L³ ) is not equal to (4/3) (pi) (L³) .
So it's pretty clear that the cube and the sphere
DO NOT have equal volumes.