Making sense of Canon's Ixus cameras

Canon currently has 9 Ixus (Elph) cameras on sale, and this is what I've observed from comparing them.

The 125, 240, 500, 510 were released in 2012 (they have Digic 5 processors).

• 500 series has 12x optical zoom
• 240 and 510 have WiFi
• 125 seems to be the same as 240, without WiFi