Hello Danielle1123
The iPhone 5S has more feature in it then the 5C. The 5c is basically a iPhone 5 but with a coloured hard plastic backing up.
The iPhone 5s has a touch ID sensor so u can unlock ur phone with ur fingerprint. It has a dual flash LED for your back camera. The specs on this device are a bit better then the iPhone 5C..
You can compare it on the Apple site below.
https://www.apple.com/ca/iphone/compare/