There's no difference.
A player is just human, regardless of nationality. Where you were born has NO impact on your performance in games, stop with this pseudo-science, please!
In random battlegrounds, chances of meeting sub-par players is HUGE. The fact that they are spanish, doesn't prove how "bad at the game lol" spanish players are, it just proves they have a big community and your bad luck of getting skilled/geared team mates for that BG.
If you want to team skilled, competent and geared players, make a premade and do Rated BGs.