The second Siamese head has a 20" bass drum, small steel snare, reversed rack toms, a gong drum as a floor tom, lower pitch octobans, 13" hats, and more unusual crashes.
The second Albino head is obviously big and loud for the purposes of playing the Octavarium songs that used the large, acrylic/steel drums of the Bonham kit.
The second Mirage and Black & Silver head uses a small steel snare, relatively large, single-headed rack tom, two floor toms, a gong drum, a bright ride, small hats, something called a "propeller," which I think is actually called a chopper, and more cowbell.
So basically kit one is metal and kit two is progressive.