AS s(a) vs. AS a

Hi all.

I see in the docs the following:
SELECT current_date + s.a AS dates FROM generate_series(0,14,7) AS s(a);

Trying it as:
SELECT current_date + a AS dates FROM generate_series(0,14,7) AS a;

yields exactly the same result.

Does the finer granularity/expressiveness offer some extra
functionality in some cases or is it a matter of style?

regards,
--Thalis