Roughly speaking, a date is a cell in the calendar and timestamp is a moment, a moment in time.
You need to understand what is required in a certain task and choose.
1. I checked into the hotel on 22 may and moved out on the 26th. Here it is about days, not specific moments.
2. Write in the logs the hit on the website is the moment.
celia.Carter82 answered on July 9th 19 at 11:06
Use unix timestamp eliminates any rake with timzone, seconds coordinate
meggie answered on July 9th 19 at 11:08
In unix t:
the absence of zones;
to date, all the way around.
Lucio answered on July 9th 19 at 11:10
If you need to perform operations with dates, e.g. add/subtract a day/hour/week, find the last day of the month, estimate if not leap-year year, find the difference in days between dates, etc. then use datetime (and such things are done quite often).
In fact, in practice, the timestamp is not too many applications, more often used datetime.