Matthias' entire back story, including his sister Myrtle, was created specifically for the cartoon and did not exist in the books.
In the book, Cluny does not know of Redwall when he first comes to Mossflower, while in the series, Redwall Abbey is why he came to Mossflower in the first place. As well, Cluny pretends to be a weary traveler in order to first enter the Abbey, and is only accompanied by Redtooth and Darkclaw. In the book, he is backed by his horde and blatantly introduces himself to the Redwallers as Cluny the Scourge.
Cornflower and Matthias have known each other for some time in the TV series, while in the book, they first met at the feast.
Cluny summons Shadow to him before he first enters Redwall, while in the book, he calls for Shadow after Cluny returns to his camp.