What is the difference between 'же' and 'и', when it comes to emphasize a word?

So i recently came across this new information about the pairs 'же' and 'и', but since they have a similar function when it comes to emphasizing words, what is the actual difference between these two?

And in which contexts should you use 'и' over 'же', or does it do the same thing no matter which one you prefer/choose?