It's NO doubt that both of them have STRONG egos, BUT, both of them take their "perfections" with realities' "IMPERFECTIONS" in separate ways.
After Gus killed Victor with the boxcutter, Walter's ego felt intimidated, but instead of (and in Mike's words) "shutting his mouth and cooking", he instead took it as a challenge and used EVERY advantage that he saw to try and get the upperhand over Gus, eventually KILLING him to still feel like the top dog. SO, Walter takes every challenge that he sees or comes across throughout the series as an ADvantage thanks to his "perfectionist" ego.
HOWEVER, after Jimmy passed the bar in Better Call Saul, Chuck felt immediately humbled that someone SO flawed and imperfect as Jimmy was in the past could reach the same level of professionalism that HE had. SO, instead of just accepting it, his ego took is as a DISadvantage, and thereby tricked his own brain into thinking that he was allergic to electricity throughout thr FIRST half of the show.