Totally different cameras, SX260 small sensor, S100 larger sensor.
Go to a camera store and try them, they is going to be a difference in feel and the controls.
The SX260 has a long zoom range, built-in GPS, but slow autofocus and not so good high ISO performance.
The S100 has better performance, but a shorter zoom range and no GPS. Tradeoff to get the features you prefer. You are going to like either if you buy it for its strong points, and if it feels comfortable to you.