The top is a great example of "Black is Beautiful," and the bottom set's cabinet color is a delicious soft caramel shade of brown...

Both cabinets here are distinguished by having been made of a thermosetting plastic, like Bakelite or Catalin, rather than the usual ABS thermoplastic that was used for most transistor cabinets...

Neither cabinet face identifies the number of transistors used in its chassis inside. The (black) TR-659 is a six transistor set that had been a five transistor set in its earliest incarnation. The (caramel) TR-10 is a four transistor set, and holding true to tradition established by US transistor mfrs for four transistor radios, this Japanese radio's cabinet face declares the set to be simply, "All Transistor."