Howl differed quite a bit. The entire war sequence was added, the ending with the witch is different as in the books the witch resolution was in book '2'. And not in a good 'we are one big happy family' way. Much of dealing with the 'king' was also partly borrowed from book 2 and partly invented. I forget the name of the 2nd book but it involves Sophie going to deal with the king, the dissolution of the witch, the freeing of the fireplace spirit, the resolution of the scarecrow as the missing brother of the king, and a trip to Wales where Howl's sister's kids are attacked.