What's the difference? I exist or live or be! Well...a vast one. Everyone exists on earth, few live and even fewer really are (Being). The difference lies in attitude to life. We take it for granted and think as if we are here forever. But there are few enlightened souls (in third category) who really know that this ain't forever, so make most of it till it lasts.
Think of this: our world confines to our immediate surroundings... we hardly ever think of the larger world existing on earth... we rarely wish to see the other colours of life across this earth. May be all that we do is to see yet another day without having a wish, without a desire, without a longing. By being full of desires, hopes and dreams, you'd start living, than just existing as an anonymous "yet another soul".
Add to these dreams, hopes and desires a thousand beliefs, convictions & passion... and what you have is an enlightened, wise, free soul who is not just existing or living... but Being. Choose your way of life and then may be you'd regret not being able to see how beautiful life is. But again, have no despair, for its never too late to Live Life.