I read the article you gave me but I did not understand pretty well, it is said that code switching is using two languages when speaking and when being a bilingual, and code mixing is the use of two languages at the same time ! in fact , I still don't see the difference?
I don't know about code-muxing but I know code-switching. It is meant to be the use of one dialect or language rather than other. It could be also using one set of vocabulary over other ones. So that, not only people, who are bilingual, but also all people can switch among their codes!
From what I know, code-switching is when someone changes from their L1(native language) to their L2 (second language) in one conversation. Code-mixing is the same thing. Some people say code-switching while others say code-mixing. Here is an example.
Me - Hi Sarah. How are you?
Sarah - I'm fine, y tu?
Me - Me? I am okay. Today es horible.
Sarah - Really? Que pena.
Notice that the words in bold are Spanish words and the regular words are in English. This is code-switching/mixing.