The Difference Between Calling and Ego
A calling comes from a place of genuine attraction to the work itself. You would do it even if no one paid you, praised you, or noticed. Ego-driven purpose comes from a desire to be seen as successful, important, or special.
Calling says: "This work matters. I want to serve it." Ego says: "This work will make me matter. I want to be seen doing it."
The same person can have both motivations for the same work. The key is honesty about which is driving in any given moment.