What is the difference of this two queries?

https://en.wikipedia.org/wiki/Car?action=raw
https://en.wikipedia.org/w/index.php?title=Car&action=raw

(i used first one before, then use second, but sometimes it's not response...)

are any of these queries doing extra processing on server side ?

which one i should use for more speed on my wikibot? (or any different query suggestion?)