Can I unlcok my iPhone 5C and get a 5?

I have an iPhone 5C, and I hate it I want an iPhone 5 because a lot of people say it's better than an iPhone 4S (and don't tell me get a 5S I don't want a 5S) and I have an iPhone 5C on contract, could I unlock the SIM, get an iPhone 5 and put the SIM in to carry on the contract?

1st off, the 5c & 5 are practically the same phone except for:
1. 5 being made with glass/aluminum vs plastic
2. 5c having a bigger battery
3. 5c having an improved camera

Just saying.

2ndly, its not the SIM you unlock, its the phone, so doing what you intended would just have you end up with a, most likely, unusable until unlocked phone.