Sleep Paralysis vs Lucid Dreaming

While we were in class discussing lucid dreaming, I had the question: what's the difference between sleep paralysis and lucid dreaming? People who have had a sleep paralysis experience say it is extremely scary and disorienting.   But, in the TEDx talk we watched in class, the speaker discussed lucid dreaming as being something pleasant and empowering.  There's obviously a difference between the two, but what exactly is it?

Sleep paralysis is where a person, during the act of falling asleep or waking up, temporarily experience an inability to move or speak.  This transition stage goes hand in hand with muscle weakness and terrifying hallucinations.  Relating to what we talked about in class-- sleep paralysis is speculated to result from disrupted REM sleep.  The body activated a temporary muscle weakness to stop you from immediately acting on your dreams.  When sleep paralysis occurs when a person is falling asleep, what happens is their mind is still awake while their body is shut down for REM sleep.  Think of it like being trapped in a dead body.  When it occurs as a person is waking up, they are aware before the REM cycle ends.  What makes sleep paralysis so scary is the vivid visions that accompany it.  Most of the time, individuals sense a menacing figure (an intruder of some sort) and on top that, are paralyzed and feel extremely vulnerable.  The figure is automatically assumed to be "evil" because during sleep paralysis, pathways in the brain become over-excited, and the mind perceives every stimuli as a threat in an act of protection.  Another possibility of a vision is an unearthly being attempting to suffocate the individual.  This happens because during sleep paralysis, the person is unable to breath voluntarily-- most because of characteristics of REM sleep that limit normal breathing.  This inability to take a deep breath is perceived as some sort of demon pressing down on the individual's chest or trying to strangle them.  

So, basically, lucid dreaming is when you are in control of your dream and have power over the outcome and content.  Sleep paralysis is when you are caught in your dream and loose control completely.