It's good to see you separating Gameboy and Gameboy color, the 118.7m Gameboy are 12/13 years of normal lifetime sales ( so two gens ) by that I mean Gameboy was without a replacement for 12 years, while its cousin snes, had been replaced in its 6th year and the predecessor of snes in its 6th year too, a normal gen has 5/6 years!
Gameboy had a revision in the end of 1998 ( gameboy color is just a gameboy with color ) which hadn't few games not compatible with og Gameboy and the games that were playable on both consoles, obviously people must preferred to upgrade to gbc to play them colored, you only had to spend again 99$.
As you have written Gameboy had sold 64.5m in nine years and another 54.2m 4/5 years of GBC about in the time frame of N64 existence.
