Differences in Canon: The ways we make a big "FUCK YOU KUBO"
1: There is no Karakura town, the game centers on real world Japan, and very well may have conflicts across the globe.
2: You can't sense the nature of someone's Reiatsu. All you can do is get a vague idea where someone is, and a rough estimate of how much stronger or weaker they are than you (assuming that they aren't suppressing their Reiatsu that is.)
3: There are no retarded canon fodder Gillian class menos, being replaced with something actually functionally intelligent at the same power level.
4: There are no 'numbered ranks' there is simply the Captain, and Officers (who are determined by having Shikai) and a Lieutenant whom the Captain chooses from among his Officers.
5: Vasto Lorde are actually fucking badass.
6: This isn't cannon. Abilities are balanced around... balance. Something Kubo doesn't seem to comprehend