Are the two spheres congruent? no, because they have the same diameter length no, because they have a different radius length yes, because they appear to look the same size yes, because they have the same volume

Are the two spheres congruent? 

I'm not sure what's being asked here. A sphere "has no hair."  A sphere's shape is completely characterized by a single parameter.  it doesn't matter if it's the surface area or the diameter or the radius or the volume; two spheres will be congruent precisely when their respective parameters are equal.  

Let's go through the list.

They have the same diameter length.

Congruent diameters mean congruent spheres.  Congruent

They have a different radius length.

Non-congruent radii mean non-congruent spheres.  Not Congruent

They appear to look the same size.

In math we usually require more than looking the same to conclude congruency.   Unknown if congruent. 

They have the same volume.   Congruent

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