Amelia when it comes to light situations the most important feature on a digital camera as I mentioned earlier is the ISO setting feature. Whether it's user selectable and what range you have to choose from. For example the Casio Z3 has an ISO range from 50 to 200 which is average the Canon has a user selectable range from 50 to 400 which allows of much better use in many different lighting situations low light to extremely bright as well as built in spot metering.
Oh yeah the Canon is 3mm thicker which is nothing and about 60grams heavier which is nothing as well.