According to Wiktionary, "ille" is mainly sed to refer to persons or things which are not near to the speaker.
I imagine a Roman citizen pointing across the street to an kindly, old weaver. The citizen says, "Ille est benignus."
According to the Latin Wikiversity course, the word "is" can also refer to far persons or things, but it places less emphasis on the distance than "ille" does.
Literally "is" means "this (one)" and "ille" means "that (one)" but both can usually be translated to "he"