In the book, Harry conserves Cedric, but is hurt as well as not able to make it to the mug; Cedric is faced with the option Harry had in the title, of taking the Triwizard Mug for himself or aiding Harry. There’s even more Pensieve scenes in the book than the motion picture; it’s compressed in the film to one scene that informs you everything you need to know, in the process removing Ludo’s backstory and also the original intro to the target market of the personality of Bellatrix Lestrange. Fudge’s rejection and outright coverup of the occasions in the maze (including Barty Jr’s supreme fate) are omitted; the basics are rather offered to the target market in movie 5.
The events leading up to Harry coming to Grimmauld Location are condensed a little bit, specifically the fight with the Dursleys over what took place to Dudley. Tonks’ being a Metamorphmagus is meant yet never completely explained or made much use other than comic relief. The cleansing of the Black residence (including the later-important detail of the locket being binned) was cut out completely. It is likewise during this chapter, I believe, where we’re originally provided the name Regulus Black; Sirius’s younger bro and a crucial “non-character” in later books. The movies give the initial mention of this name to Slughorn as an offhand line in HBP. Percy’s estrangement from the Weasleys from the title is mostly overlooked in the film; he’s the one holding Harry in Dumbledore’s office when Ms. Umbridge challenges Dumbledore concerning the DA, and therefore he’s an adversary, but besides a laterally glance by Harry at his captor, that fact is never overtly given the target market’s focus.