If the Earth's axis were closer to "straight up and down" than
the present 23.5°, then . . .
-- The areas around the north and south poles where the sun
can be up or down for more than 24 hours would be smaller.
-- The "Tropic Zone", between the Tropic of Cancer and the
Tropic of Capricorn, where it's possible for the sun to be
directly overhead, would be narrower.
-- There would be less difference, everywhere, between the
lengths of daylight on the "longest day" and the "shortest day"
of the year.
-- The seasons would be less extreme everywhere. There would
be less difference, everywhere, between the coldest part of the
Winter and the warmest part of the Summer.