In fact, there is a big difference between Barcelona in the Champions League and La Liga. I think one of the reasons is that La Liga teams are relatively far behind Barcelona. Barcelona are beating them fearlessly. But Barca could not be ready for the Champions League yet. The upcoming match against Real Madrid will show how successful Barca is in La Liga.
The debate on Barcelona's performance in the Spanish League is not in this topic. But I think that as things are, if they lose against Real Madrid, and they don't manage to continue in the Champions League (very likely), they will have a very similar season to the previous one.