Yea there is a difference between Nigga and Nigger. Nigger is who whites and other non-black refer to Blacks. Its filled with so much hatred, stereotypes, history during slavery and during the Civil Rights Movement - it evokes much emotion instantly.
Nigga is something that we call ourselves. Something that nobody else could or would call us, nor could they call themselves one since it derived from a time when our family members & ancestors were enslaved.
Mainstream America has always dipped in to our culture and used what they wanted. Take music for instance (Ex. Elvis). Rap music. In the late 1970s everyone said it would last. Now corporate america incorporates it everywhere (commercials, tv. shows etc), Fashion, etc.
It appears now that folks are try'in so hard to walk in our shoes. Doo rags/wave caps, saggin, talk, walk, etc. The opposite isn't true. You dont see Blacks tryin to be like Latinos, Asians, and Euros by imitating their cultural. Somthing to think about....