The midquel is set in a timeline similar to, but ultimately distinct from the original film.
This would explain the more humanized personalities of the characters and general nature of the forest being somewhat different from that of the original film, but the events before and after the midquel still play out similar or identical to how they did in the original film, so that the two films could technically still work in tandem as a continuity and not have to worry about sweating the differences between them too much. Alternatively... The midquel is only Semi-Canon to the original film.
The general events of the midquel technically happened in some form, but how it literally played out would end up being different from how It was depicted in the film, and certain elements of the midquel would be considered either apocryphal or flat out non-canon to the overall timeline.- Sort of supported. The Interquel is not part of Disney Animated Canon, with all supporting material of it's films excluded from it of debatable relation.
Alternatively, the midquel is the same universe from a character perspective.
- The first film conveys nature much more as we see it, based on instinct, with only a few blemishes of humanity to give it personality like odd moments of the animals talking. The second conveys nature from the animals' mindset, we see their motives and emotions, making the whole piece seem far more character driven by showing us how the world looks through their eyes.
The Interquel was intended to be Entry 46 of Disney Animated Canon
Bambi II had much more time, budget and elaboration put into it than a standard Disneytoon Studios sequel, with even some of Disney's mainstream staff brought in to supervise. Europe in fact released it theatrically and publicised it as much as a standard main Disney film. Upon realising the US had decided to give it a more humble Direct-to-Video release however, they quickly aborted, with The Wild of the same year (a rather loose creation of Disney) ending up Europe's divergent entry in it's place. The Groundhog and the Porcupine are the same character.
After Ronno frightened him for no reason, the Groundhog became very bitter and grew spines that he didn't have during the winter. It helps that they're both voiced by the same guy.