The Prophets seem like they are creatures that live in the 4th dimension, which is time. If this is the case, then these creatures would exist in all times at once, while us, being only in the third dimension, can only see a slice of time, giving us the perception of a distinct present. The Q live in the third dimension it seems, they have a distinct present and sense of time. I don't think they can really be compared, because how can you compare how the two of them work, any better than you could compare how us and a two dimensional creature do?