Hi, "each day" and "every day" can often mean the same thing. The difference is that "each day" usually focuses more on the individual days, while "every day" usually focuses more on a routine or habitual action. For example: "I practise my English every day (habitual/general routine). Each day, I learn 10 new words and use them in a sentence (focusing on specific actions done on each day)." I hope that helps!