What's the difference between the iPhone 5S an the iPhone 5C?

Other than color.
Do they both have the same functions? Or is the iPhone 5C a cheaper version of the iPhone? Does it come with less?

If there really is no difference other than color… Would you get the 5C or 5S? I'd be worried that I'd get tired of the color on the 5C and that I might rather have the 5S gold because it looks nice and it's a more neutral color that would go with a lot more things.

I'm just having trouble deciding!

The iPhone 5S is made of high grade aluminum.
iPhone 5S has a new A7 64 bit system chip that's twice as fast as the iPhone 5 A6 chip.
iPhone 5S TouchID - use your fingerprint on the home button instead of a password.

iPhone 5C is made of hard coated polycarbonate material and steel reinforced.
It contains the same A6 processor and 8 megapixel camera as the iPhone 5.

Okay, so the main difference between the iPhone 5S and the iPhone 5C is the hardware. The iPhone 5S has all new processors, the M7 chip, and 64-bit computing. The iPhone 5C has the same hardware that the iPhone 5 has. Another difference is the design. The iPhone 5C is made of aluminum, and the iPhone 5C is made of a polycarbonate material (plastic). The iPhone 5S also has Touch ID (using your fingerprint to unlock your phone), while the iPhone 5C doesn't. If you want the best phone that Apple has to offer, get the 5S, if you don't mind having a phone with older technology (but it is more durable), then get the iPhone 5C. I think you will be happy with both, just be sure you get a color that you will love for a while if you get the 5C (but you will also be able to cover it with 3rd party cases if needed).
Check this post out for more information about the iPhone 5S: http://techforteenagers.com/iphone-5s-first-impressions/