Assuming normal function within the organic platform, a sequence of physical and mental experiences make up the existence we call life. A common thread indeed it is...this thing called life. An organismic state characterized by the capacity for metabolism [all that ATP to ADP] , reaction to stimuli [our five senses], growth, and of course reproduction. As genealogist, we often record it as the period of birth to death, and spend a great deal of effort tracing and recording these aspects of our own ancestors.
Simply put, life is our existence as we know it. Existence is our reality as we experience it. Existence is our conscious perception of our environment that surrounds us. Sight, sound, taste, smell, and touch all provide input from this environment. Input comes from a variety of external sources which affects the experience we know as life. A specific phase of earthly existence that is certainly shared among us all as threads that bind.