The 88 had a greater ceiling.
Depend on wich variant, the 90 mm italian gun had a heavier projectile projected at 850 mps, compared with the 820 mps of the flak 36, the 88mm Flak 41 is better than both however.
There were a lot of AA guns in its class that were better than the 88mm in pure, or theoretical, AA performance. I think the notoriety of the 88 is -being a bit overrated as a ‘super-weapon’ IMO- not because of any superior performance as a gun, but in its low weight, ammunition, versatility, and the training of the crews manning them
The notoriety is evidently as antitank weapon.