Eight wordly winds, tanha or upadana? In essence, the concepts of


eight worldly winds
tanha
upadana


seem to describe the same phenomena. 

Is there a specific reason that they are described separately?
To me, these are three entirely different things. 

Eight Worldly Winds are an allegory for a list of egoistic concerns, like being obsessed with fame, blame, etc.

Tanha (thirst) is a metaphor for craving something unattainable, in other words an inner conflict between "is" and "should".

Upadana (fuel) is a metaphor for "feeding" an unhealthy state of mind by repeatedly thinking about topics that sustain the state.

While in some situations they may occur closely together, they refer to three entirely different phenomena.