Summary of Code Mixing and Code Switching

Code mixing is combined two languages, or changes word, phrase or utterance to another language.
Code switching is change sentences to another language (keseluruhan)
Obvious change because the situations.

For example, suppose i know Hindi and English:
 Code switching: 

"Ram is a good boy aur bahut achchhi painting bhi karta hai."

Here the 1st part of the sentence is in English and second part is in Hindi, that is we have switched from English to Hindi.

 Code mixing:

"Ram is eating aam and playing with sita"

Here what happened, I am borrowing a word 'aam' (meaning Mango in English) from Hindi and adapting it in the English. Grammar of Hindi didn't get involve. Only lexical item of Hindi is embedded in English.

Code switching is a universal language-contact phenomenon that reflects the grammars of both languages working simultaneously.
Code mixing is also a language contact phenomenon that doesn't reflect the grammars of both languages working simultaneously. Here, we borrow words from one language and adapt it in other language.

Code switching and code mixing is possible in bilingual or multilingual environment, not in monolingual environment.
As because it is not possible to either switch or mix in the same language. At least two languages are needed for the above process to happen.
For instance, the bilingual children go through the mixing at their early stages of learning. While adults after becoming competent in at least 2 languages, they show their performance of their learning by switching from one language to another.