SW and CM are the two (remaining) characters with Infinity Stone derived powers, not a surprise they had the best raw advantage
And 2014 Thanos is less traveled in this fight, but he is absolutely more ambitious as he saw his future and grew arrogant by his certainty at the inevitability of his victory, like he's just retracting steps he's already taken. And the stones are already collected this time, right there for the taking, its like all realities bend toward his own goal. Thor lost in IW by making it personal and giving one last speech instead of finishing it-
Thanos does it in Endgame, both making it personal revenge "what I am going to do to your stubborn planet, I'm going to enjoy it" and taking an early victory lap to say "I am inevitable" without making sure the stones were even there.