"Broadway" is the Wii CPU, "Gekko" was Gamecube's.
Essentially, the former is a shrunk, higher clocking variation of the same PPC G3-based design.
Wii's "Broadway" only has half the L2 cache of the PowerPC 750FX design (or 1/4th that of the PowerPC 750GX), and the L2 bus width was cut down.