Disney seems to have a fairly consistent visual style thorugh the majority of its main works, ignoring any earlier films where they weres till refining their image. Their main feature films seem to follow a fairly realistic style, human characters having consistent proportions to human anatomy, with some exaggeration for effect when necessary. This style is evident across a wide range of their feature films.
In Snow White, seen above, the main characters of Snow White and the Witch have incredibly realistic looks that aren't too alienating to audiences. Only when the Witch transforms herself does her appearance become much more exaggerated and cartoony, to accentuate her grotesqueness, yet still she does not appear too threatening or repulsive. The dwarves characters follow a very different style guide to the main characters, having features like large ears, large red noses, and big cheeks. They seem to have been designed to really embody the varying personalities given to them. Yet, still, they remain very 'safe' in their design, with uniform features such as their large eyes designed to appeal to people, as well as their mouths.

Many Disney features follow this same path, with main characters having very realistic and 'human-like' designs, whereas ancillary characters are more 'cartoony' and designed to appeal mainly for comedy purposes. In the film Beauty and the Beast for example, the character of Belle again has a human design. The Beast is obviously a more stylized character, as he is intended to be more threatening, having a large stature, yet he still seems quite reserved in his design, not being a character designed to be truly 'scary' in any sense. Opposed to this is the side-characters, consisting of the various inanimate objects the other characters have been transformed into, are obviously much less human, but retain human characteristics that make them easier for an audience to empathize with.
Though it brought the company a lot of financial success, I believe this approach, of contrasting more naturalistic characters against the exaggerated to be disadvantageous, the gulf between designs becoming extremely noticeable at times, pulling the audience out of the film.
Some Disney features have eschewed using the common established look in favour of slightly more radical designs. Disney's Hercules (1997) took a lot inspiration from Greek design and the shapes used in much of the historical imagery of the time the tale was based in. As well as this, their film Atlantis: The Lost Empire had Mike Mignola, most prominently known as the artist of Hellboy, do the character design for much of the film's cast. Both these processes resulted in much more angular and harder looking characters than had been seen before in a Disney Movie, and for the most part seemed to overcome the previous problems of inconsistency in character designs, resulting in, I believe, much stronger visual appeal. However, both these films were less successful at the box office than many other Disney films, in the case of Atlantis quite significantly more so, perhaps resulting in a message being sent to Disney that these kind of stylized designs were not worth pursuing.

Essentially what this boils down to is that for the majority of Disney's films, there is a lot of consistency in the way characters, particularly main ones, are designed. As seen above, it's clear that all of the 'Disney Princesses' have a very similar set of rules in terms of their design, some of them even having almost identical facial features. It seems that at some point Disney found a groove for their design that was successful, and obviously continued to work this way for many years, perhaps because of the sense of familiarity it brought both film-makers and audiences.
-All images sourced from Google
