Real madrid didn't make much signings as Barcelona this season, Ancelotti did mention that he was satisfied with the players he had already and with few additions he was ready to kick start the season, those statements he made turned out to be right and proves he knows what he is doing. The current players in the team have shown satisfactory performances this season. Barcelona also have shown improvement this season afteraki g several signings this summer and before. As the season grows old we will see how well both teams have improved and who is the favourite to win the trophy.
Real Madrid haven't changed much because their squad is still solid with lots of quality players. even Marcelo leaving didn't have any impact on the madrid squad. but in barcelona they really need to bring in quality stickers to be able to spearhead the attack and the signing of lewandowski has had a good impact for barcelona at the start of this season. even Lewandowski until the 7th round of matches earlier this season he was already listed as the temporary top scorer. so in this comparison real madrid only needed a small change at the start of the season whereas barcelona had a big change in the squad.
Yes, Real Madrid didn't change in their squad neither was there a change in their pattern of play this season this is because the team is surrounded by quality players who has made up their minds to give their best to the team regardless of when they are called upon to play. The reason why Marcelo's departure didn't affect Real Madrid was that before his departure he was no longer a regular palyer for the team so his replacement filled his gap even before he left the team.
The signing of Robert Lewandoski brought good changes to the Barcelona team because with him so far the performance of Barcelona has improved better than last season that they were struggling to win matches, Barcelona made a good number of changes but Real Madrid team has been good shape since last season even till date.