Being preoccupied does not really mean absent mindedness. It could imply that you are engrossed, and in this way, preoccupied. It could imply that you are effectively diverted by musings, individuals and outer occasions, because of absence of core interest. It could likewise imply that you are drained and depleted following full time work. 
RE: What is Absentmindedness and How Can We Live in the Present?