Jealous vs Envious (adjectives )

Are jealousy and envy unwelcome feelings ? Can they be used interchangeably ? Why do so many people suffer with jealousy ? Do you remember any proverb which can illustrate the meaning of an envious neighbour very well ? Do you know anyone who is always envious of what you get ? 

http://www.macmillandictionary.com/dictionary/british/interchangeable#interchangeable__4

You can get a very nice explanation about the use of these words : envious and jealous if you click on the link below.

Homer Simpson also points out this difference very well on the video you can watch at the bottom of this post,ok ?

Enjoy !

http://www.merriam-webster.com/words-at-play/jealous-vs-envious