The competition between these two teams seems unfair because they both have very large differences in team quality, so they are not comparable so there is no fierce competition.
In La Liga, only Barceona and Atletico Madrid are able to compete with Real Madrid and when these two teams are down this season, Real Madrid will easily be at the top of the standings.
This is the same as what happens to several underdog teams competing at the top of the standings and even competing for the championship title. The quality and depth of the squad will make a difference in the consistency of play. A strong team like Real Madrid can rotate players a lot and use various tactics because they have many great players who can adapt to game tactics. And an underdog team like Girona must be able to show the best performance from their main squad to be able to compete at the top of the standings. And if they make a mistake or the main player is injured then it can make their performance decline. I think the only way that an underdog team can win the title is if the performance of a strong team declines in that season or the team is able to play solidly collectively like Leverkusen did in the Bundesliga.