The films which are classed as Walt Disney Animated Classics are the ones which were made by Walt Disney Feature Animation. The full list is as follows:-
Snow White
Pinocchio
Fantasia
Dumbo
Bambi
Saludos Amigos
The Three Caballeros
Make Mine Music
Melody Time
Fun and Fancy Free
The Adventures of Ichabod and Mr. Toad
Cinderella
Alice in Wonderland
Peter Pan
Lady and the Tramp
Sleeping Beauty
101 Dalmatians
The Sword in the Stone
The Jungle Book
Robin Hood
The Many Adventures of Winnie the Pooh
The Rescuers
The Fox and the Hound
The Black Cauldron
The Great Mouse Detective
Oliver and Company
The Little Mermaid
The Rescuers Down Under
Beauty and the Beast
Aladdin
The Lion King
Pocahontas
The Hunchback of Notré Dame
Hercules
Mulan
Tarzan
Fantasia 2000
The Emperor's New Groove
Atlantis
Treasure Planet
Lilo and Stitch
Brother Bear
Home on the Range
Chicken Little
Meet the Robinson's
So while Feature Animation probably worked on Mary Poppins, it's not classed as an Animated Classic. And 101 Dalmatians had nothing to do with animation.
The term Walt Disney Classics has been a bit more loosely applied in some locales than others. In the UK, The Wild was classed as an Animated Classic, but it was made by a different animation studio and just released under the Disney name.