Q: why is there such a big difference in the usage from what Itunes says and what my iphone 5C says?

Hello El Ferretto,

I'm sorry to hear you are having this issue with your iPhone. I also apologize, I'm a bit unclear on the exact nature of the issue you are describing. If you are referring to the storage space available on your iPhone, you may want to double-check that you are viewing the storage space as listed in the following article, and see if you are still seeing the discrepency: 

See how much storage you've used on your iPhone, iPad, and iPod touch - Apple Support

Sincerely,

- Brenden