Actually MySQL provide a lot of easy to use function in daily life without more effort from user side-
NOW() it produce date and time both in current scenario whereas
CURDATE() produce date only, CURTIME() display time only, we can use one of them according to our need with CAST or merge other calculation it, MySQL rich in these type of function.
NOTE:-You can see the difference using query select NOW() as NOWDATETIME, CURDATE() as NOWDATE, CURTIME() as NOWTIME ;