The word envy refers to a disagreeable feeling or jealousy with regard to someone else's success or their possessions. It is not an attractive quality and is considered to be one of the seven deadly sins. The word envious can be used to describe the feeling of envy.
Ex: When the award went to my brother, I felt envy. All my affection for him fled as I realised that his efforts had surpassed mine.
Ex: Paulette was envious of the other girls in our class. It seemed that their work never disappointed the professor as hers did.
The phrase to be the envy of is used to refer to something that people are jealous of.
Ex: My new car is the envy of the school. Other students were yearning for a ride and were clearly jealous.
Ex: Paula's new dress is the envy of her sister. Her jealousy is beyond belief, and she should not be allowed to borrow it.
The word greed means excessive want for money and/or possessions. It is a negative attribute and considered to be one of the seven deadly sins.
Ex: His greed led him to do terrible things. The drive to make money wreaked havoc in the lives of his clients as he invested their money inappropriately.
Ex: Greed is a powerful and terrible thing. You will end up struggling with your conscience and losing loved ones if all you care about is money.
The word greedy is used to describe someone who exhibits greed. In this case, it can refer to the excessive desire to have more of anything, not just money and possessions.
Ex: You are so greedy! Fran will be really disappointed if you eat all the cupcakes so do not eat them all.
Ex: Someone should have told me how greedy Tim is. I did not know that he would chase the professor around campus and take all of his time away from other students.