"every day"--tells you that some occurrence happens each day, e.g. "I walk by this school every day." "everyday"--an adjective modifying some noun that tends to connote "commonplace" or "ordinary," e.g. "As an engineer, he had trouble grasping the nuances of everyday conversation." These two uses, though bearing some close relationship to each other, are in fact not the same. Thank you, and good day.