How would one know if they had alcohol induced pancreatitis or one from an infection?

If you drink alcohol, it is the likely cause of pancreatitis. There are few infections that cause pancreatitis. Alcohol is a poison that never did anybody any good, ever, so stay away from it. It will destroy your brain cells, damage testicular cells that make testosterone, facilitate development of cancer in many organs, cause hepatitis, cirrhosis and pancreatitis etc. There is no safe level.