Is my iphone defective? Or an iphone 4 or 4s?

I have recently purchased the iphone 4 from my local radioshack. I was researching to find out what the difference between the iphone 4s and 4 and found a physical trait. My iphone has four "antenna" that the iphone 4s has, but my iphone is just the 4. Siri and the little slot on the right side are not "included".Is my iphone a defective? Please, if anyone, answer my question.thank-you

I fail to understand why you think it is defective. You bought a 4 not a 4s and it functions like a 4, what is the problem?