I'm not going to make a point about how the two terms are different - Melanie Klein already did that in a very specific manner. What I will reflect is the way to deal with it.
Lately I've been envying a lot, because I realized that many people around me seem to have everything together; they are on a path of certainty and security, or they seem settled with life, and they seem to have it all going, etc. There are just people in your life that you see and you wonder how blessed, fortunate, or lucky they are, and of course in your own definition of what these mean.
I think acknowledging this envy is important. This is what Klein said. To be aware of your envy may help prevent you from destroying relationships with those whom you love. But there is another thought.
Example. If I were to envy someone because of the expensive watch that he wears, my envy will not be satisfied by purchasing the same watch. My envy will go away after I make a purchase that is better than what he has. After that purchase, I can no longer go downward, I will continue envying someone with an even more expensive watch and make comparisons until I own the best and only watch for me. Then, I will start envying another man's pair of shoes. The cycle continues.
I thought, what if, after acknowledging my envy, I learn to be satisfied and content with what I have? Won't that solve the problem? Because now I know that feeding my envy will not save me from it, but instead will continue to fire my endless desire.
But learning to satisfied or to be content is not the easiest thing to do in the world. Everyday, especially lately, I have to ask God to remind me about His goodness and all the good things He has provided and blessed me with. As I look towards what others have and fantasize about living their lives, I forget that there are other people who are looking towards me and fantasize about living my life, because I live a blessed life as well.
So rather than being caught up in a cycle that I wasn't meant to be in, I might as well focus on myself and remember all the goodness that God has poured in my life, and believe His promise when He said that He has everything figured out for me.