According to Robert J. Vallerand's Dualistic Model of Passion, passion has two main flavors: harmonious and obsessive.
Those with harmonious passion engage in their work because it brings them intrinsic joy. They have a sense of control of their work, and their work is in harmony with their other activities in life. At the same time, they know when to disengage, and are better at turning off the work switch when they wish to enjoy other activities or when further engagement becomes too risky. As a result, their work doesn't conflict with the other areas of their lives.
Obsessive passion is a different story. Like those with harmonious passion, those with obsessive passion perceive their work as representing a passion for them, and view their work as highly valued. A major difference is that they have an uncontrollable urge to engage in their work. As a result, they report feeling more conflict between their passion and the other activities in their life.
Both forms of passion are associated with very different outcomes. Harmonious passion is associated with higher levels of physical health, psychological well-being, self-reported self-esteem, positive emotions, creativity, concentration, flow, work satisfaction, and increased congruence with other areas of one's life. These effects spill over into other areas. Because people with harmonious passion can actively disengage from work and experience other parts of their lives, they report general positive affect over time.
In contrast, those with obsessive passion display higher levels of negative affect over time and display more maladaptive behaviors. They report higher levels of negative affect during and after activity engagement; they can hardly ever stop thinking about their work, and they get quite frustrated when they are prevented from working. They also persist when it's risky to do so (just like a pathological gambler). A reason for this is that their work forms a very large part of their self-concept. To protect their selves, they display more self-protective behaviors, such as aggression,especially when their identity is threatened. Those with obsessive passion also have a more negative image of themselves, being quicker to pair the word "unpleasant" with "self" than those showing lower levels of obsessive passion. This suggests that their persistence doesn't come from a place of intrinsic joy, but an unstable ego.