If we look at the points, it really won't affect their position. Real Madrid will remain in first place and Barcelona as runner up. However, this is El Classico which is always a prestigious match and a place to show off who is stronger in the match. Always high tension when it comes to Barcelona and Real Madrid. That's why El Classico is always interesting because there is a deep rivalry between the two. 
In my opinion, in this week's El Clasico match, Real Madrid wants to ensure it with a win and doesn't want to delay their climb to the La Liga championship. We know that Real Madrid will still be very busy after successfully qualifying for the semifinals of the Champions League and they don't want their target of winning the La Liga title to hinder them and even though their opponent is Barcelona, they definitely want to beat Barcelona again like in the previous meeting. Apart from that, Barcelona, who are still obsessed with Real Madrid, will definitely make this match an opportunity for revenge and they have to finish it before the season ends. Moreover, they still have a chance to put pressure on Real Madrid. But yeah, the chances will not be big and it will be impossible to catch Real Madrid. So I think anyone can win and what is more important is how both teams can provide an attractive performance with the history and prestige that they always carry in every meeting.