The point I can catch is that Real Madrid is more trusted as the final winner against Dortmund. You are trying to describe the situation of a final by comparing the Atalanta and Bayer Leverkusen matches in European League.
Right if the final match will feel different even though Real Madrid is known to be tough when playing in the final round. I think the chance to win is still 50:50 between Dortmund and Real Madrid.
Dortmund is very strong in terms of defense. Real Madrid is great in attacks with the number of goals made in UCL. That is, the two teams have advantages and disadvantages of each. For me, for now I don't have to win Real Madrid or Dortmund, but how strong is our analysis to win the bet we will make.
Speaking of the bet... I think that in this match there will be more than 9.5 corners and Madrid will win... If you bet now, the odds are around 3... I think I will take a risk and bet on these events... Probably a good bet that both teams will score... I don't remember Champions League finals when Real didn't win... Dortmund won in the last millennium...

I will place a 1x2 bet. Corner bets don't like it. Both teams can score goals being the favorite choice.
I will not rush into making a decision in betting on this match. I will still wait a few more days.
Indeed, Real Madrid rarely loses every time they play in the Champions League final and I admit that based on the data I have found regarding the teams that win the UCL trophy from season to season.
This is the season where Real Madrid played in the final and were only satisfied as runners up.
- Season 1961/1962 vs Benfica.
- Season 1963/1964 vs Inter Milan.
- Season 1980/1981 season vs Liverpool.
Meanwhile, Dortmund only played in the final twice with the results being 1 winner and 1 runner up. UCL champion Dortmund against Juventus in the 1996/1997 season. Became runner up when they lost against Bayern Munich in the 2012/2013 season.