Thank you all for replying!
I do feel there is some hard-to-define, hard-to-detect-whilst-dreaming, subtle 'feeling' that is present in dreams that is not present in waking life. Or maybe it is the other way around (that this alert-aware type feeling is absent from dreaming life)
It's hard for me to pin down. At the moment, the best I can recall and describe is that it feels somewhat like 'autopilot' does in waking life - when I'm not really thinking, I'm just doing - for example at work when I'm doing repetitive actions that require minimal thought (but some thought). So maybe, it's a 'thinking' thing as well, like how JoannaB describes;
oh cool I got six fingers, I must have grown an extra one over night
It's like the thinking part of the brain distracted.