When do we use ''los demás'' versus ''los otros''?

Hola Aarti

Both "con los demás" and "con otros" are equally correct when it means "with others" as in "other people in general". If you use the article "con los otros" that would mean that you're referring to a specific group of people, so you're identifying who those others are. So it doesn't work that well using the article "los" in this context as in "with others" as a general (unknown) others. 

For example:

No quiero estos, quiero los otros.

I don't want these, I want those other ones (over there).

I hope this clarifies your doubt. 

Bear in mind that with "los demás" we always use the article, whichever the context.

Saludos

Inma