The difference between Ronaldo and Messi is the fact that Ronaldo realized his physical decline, while Messi didn't. Messi desperately tries to be the same player as he was 10 years ago and since he cannot do the things he used to do in the past and he needs more carrying for being able to even get into the position of scoring a goal. Ronaldo could still try to beat players left n right, cut inside and scoring those rocket of a longshots etc, but he realized he's 30, it's time to adapt just like every athlete should do when getting older. Messi hasn't adapted a bit, the whole team around him had to adapt to him and that always creates problems with the starting squad, the players coming n leaving his teams, especially in NT.
Real Madrid never put a team around Ronaldo and instead, if im not mistaken they sold all the players Ronaldo enjoyed playing with. I remember Ronaldo calling Ozil one of the best players he's played with, Di Maria also being at RM during those times. Higuain was also there. RM bought multiple players 2009, was it Ronaldo, Kaka, Benzema and Xabi Alonso or some shit and after that, Bale was almost only guy they really invested for a long time. Then James was one, but they never built their team around Ronaldo, because it was unecessary. Wasn't it even that Perez didn't want Ronaldo in there in first place, or it really wasn't his "galactico signing", so they always had somewhat cold relationship, which prob was the main reason Ronaldo wanted to leave. They prob thought at RM that when signing bale, he would be the successor for Ronaldo but they never thought Ronaldo would still be playing at 35 at this level so their plan didn't work out. Now when Ronaldo came to Juve, the first big signing we did for making him to score more goals was MDL, which would run down the flanks and provide +20 assist a season for him, just like Barca does by investing on their defense yearly, by signing these all these Coutinhos, Villas, Henry's, Zlatan's, Griezmann's, Dembeles, Neymar's etc.
Portugal also did the same, by bringing in Fernando Santos, the notorious defensive mindset which is all about result, and Ronaldo adapted to his system with no question asked meanwhile Messi, demanded some Barca's B coach to their NT for having somewhat similar system to Barca.
Now since Ronaldo has enjoyed about the luxury of these teams built around him, i think it's fair that Barca continues to bring players just for Messi next 4-5 years atleast, so it would be somewhat even.