Besides $10, how are these different?

[tju1973]

I am eye weary, but how are these really different?
http://www.dsarms.com/DSA-ZM4-A3-Up...--M4---DSZM4CBUPARK/productinfo/DSZM4CBUPARK/

http://www.dsarms.com/DSA-ZM4-Forged-7075T6-A3-AR15-Upper-Receiver---DSZM4CBU/productinfo/DSZM4CBU/

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$10 aint much, but how are these different?

 

[Tirod]

Parkerizing

 

[tju1973]

doh! I looked at them for like 10 minutes, and they looked the same..guess they are EXCEPT that..