Powerlessness is the pain of the Soul before God. Of course we can apply this in a mundane way to imply that we are unable to change things. So we succumb to the bureaucracy at work, even while we see the need to change something, because the department is run by someone else and our hands are tied.
Powerlessness also applies to defencelessness, in the sense that one is compromised by brute force and is not able to respond in kind. One becomes helpless, so to speak.
I take it that you mean 'grey'. Greyness implies not clear-cut, unsure. It can also mean dreary, dark, relating to the weather, and also melancholy to express a sad state. In my poem, My Friends Have Become Strangers, I refer to the sun as being engulfed by grey mists. In other words, the light has gone out and is replaced by despair, a very sad state.
A grey life is dull, lifeless, seemingly without hope and lacks vibrancy and enthusiasm. At such times it can be thought of as powerlessness, yes, but there is still some control. Powerlessness is deeper, more profound, and like the Soul, control is generally in the hands of someone or something else. Hope this helps.