What is the difference between a greedy algorithm and an np completely problem

Question

or better ask:
does an np completely problem always end in a greedy algorithm?
if a problem is not np completely there is always a better algorithm but greedy?

Answer 1

These are the different types of classification. They cannot be compared. All the greedy algorithms have the similar type of behavior, and all Np completely algorithms are algorithms with the same algorithmical complexity.