Is Alice from wonderland a disney princesses?

Nope, she's a Disney heroine like Megara, Esmeralda, Kida, Anna, Elsa and others

No, Alice isn't a Disney Princess, she's a Disney Heroine.

The Disney Princess (or DPs) are in order;
Snow White
Cinderella
Ariel
Belle,
Jasmine
Pocahontas
Mulan
Tiana
Rapunzel
Merida

Anna and Elsa were suppose to join but because Frozen got so popular, they never did. Moana might join, but that's yet to be seen.

As for the difference between DPs and Disney Heroine (DHs) are;

1. Most of the DPs movies have done well at the box office. There's one or two DPs movies that didn't do well, but are still well known. As for the DHs, their moves are either not that well known (Hercules) or too dark (The Hunchback...)

2. The DPs either start out as princesses (Snow White, Jasmine) or are made princesses by the end of the film (Cinderella, Belle). Mulan and kinda Pocahontas don't really follow this one.
However, Mulan is included because the line-up needed a Chinese person, because she's saved China and also because The Emperor in the movie more or less said she now had high status because of her actions.
As for Pocahontas, she's kinda sorta a princess if you twist it around a bit.

I'm sure they're more differences, but those are the biggest ones (I think).