date and time
Used for scheduled events, meetings, departures, etc., specifying both the calendar date and the clock time.
The date and time of the meeting haven't been decided yet.
Please let me know the date and time of departure.
days and hours
Refers to a span or collection of days and hours, often in contexts like opening hours, business days, or duration.
Business days and hours are Monday to Friday, 9 a.m. to 5 p.m.
We decide the date and time of the meeting.
We changed the departure date and time.
The date and time of the interview has been set.
Please specify a date and time for the delivery.
We will inform you of the event's date and time.
日時 specifies both the date and the time of an event, while 日にち refers only to the date itself, without a time attached.