Although these two cameras have the same sensor, they have very different lens design. The S1xx series design focus on miniaturization while the G series traditionally focus on image quality. The lenses can make all the difference in the image quality.
For the G15
- Lightning Quick AF (one of the fastest for a PnS),
- Sharper Lens rendering more details due to larger lens elements.
- Faster Lens. You can use higher shutter speed - less camera shake.
- Bokeh. According to
dpreview, this camera can render more bokeh at 140mm than APS-C and m43 cameras and their kit lenses. Yes this includes the G1X at its tele end.
- Better dials and controls for quick settings change.
For the S110
- Compact Pocketable design (a.k.a 'wife friendly' to some men)
- Touch screen interface can be intuitive and easy to use.
- Wifi to transfer files directly to your iOS/Android devices (in hotspot mode) without additional cables, etc.
- Wider lens at 24mm. This additional 4mm difference could mean moving quite a few meters back (eg. 5-10m) when you zoom with your own feet. That may not be possible when you are traveling and there is a cliff or fixed structures behind you. This could also mean cutting away five of your aunties in a family photo (with extremely naggy consequences). You can always crop if you fall short on the tele end but you can never post process to emulate a wider lens.
- Cheaper. This is very very important to many. At first I thought the Sony Rx100 will destroy the S110's market completely, but the price premium on the RX100 has kept the S110 quite popular.
