In the Spanish football league system, La Liga, Real Madrid and Barcelona have dominated their respective teams over recent seasons, with Real Madrid leading by a goal difference of 21 points in La Liga this season. With this impressive performance, both Real Madrid and Barcelona have secured their places as the top two clubs in La Liga for the first time in their history.

The goal difference between Real Madrid and Barcelona is one of the most significant factors in determining who will win the title in La Liga this season. The two teams have been consistently performing well throughout the season, with Real Madrid leading the table by a comfortable margin after winning five out of six games.

However, it's important to note that the goal difference doesn't necessarily determine the outcome of a match. Both teams have strong attacking players and can score goals easily against defenders who don't perform well defensively. In fact, the two teams have been able to score multiple goals in the last few weeks, showcasing their ability to create chances and score goals on the counter-attack.

Barcelona has also had a strong season, with Lionel Messi scoring a total of 64 goals this season. However, the team has struggled to find consistency in defense, which could be a factor in their success this season.

Real Madrid, meanwhile, has faced some tough competition from other teams in La Liga. However, they have shown resilience and determination to keep up with the best teams in the league. They have been able to maintain their position at the top of the table despite facing some tough opposition.

Overall, while Real Madrid and Barcelona have performed well this season, there are still plenty of challenges ahead for them to overcome. With the goal difference being so close, it's likely that either team will struggle to keep pace with the other in the upcoming matches. However, with the right approach and strategy, both teams have the potential to compete for La Liga titles this season.