Answer:
The cube has the greater volume.
Explanation:
The volume of a cube is given as:

Where
is the measure of 1 side (all sides of a cube are same)
The volume of a rectangular solid is given as:

Where
is the length,
is the width, and
is the height.
From the problem,
- Volume of cube =
[since each side is given as 4]
- Volume of rectangular solid =
[the length is given as 8, width is 2, and height is 2]
The cube has the greater volume.