“Jon Snow is NOT Aegon Targaryen, Young Griff is! Stupid writers!”
Also in books - (this is all just off the top of my head, I know I have missed a lot)
Catelyn Stark is still “alive” as Lady Stoneheart.
Beric Dondarrion died giving Catelyn the kiss of life.
Lady Stoneheart now leads the Brotherhood without Banners and despises Brienne of Tarth and demands her head.
Robb Stark never fell in love with Talisa - Talisa was never even a character. Robb had a moment of weakness and slept with Jeyne Westerling, a high born, and was afraid that she would be pregnant, and married her to prevent a bastard.
Jeyne Westerling was never pregnant, she was not at the Red Wedding, and she was never killed. She was held captive for two years to make sure she had not given Robb an heir.
Cersei aborted her baby with Robert because she hated him that much. So no, she is not the blonde woman that used to sing to Gendry as a baby.
The Mad King never once said “burn them all”
All Targaryens (as they have the blood of Old Valaryia) have purple eyes. This is incredible important in identifying that they’re actually Targaryens and not pretenders.
Margaery & Loras are not the only Tyrell heirs. They have an older brother who was supposed to marry Sansa. (And also another brother) So even if / when the wild fire scene happens in the books, the Tyrell house will live. They have dozens of distant cousins with the name Tyrell. I have no idea why they decided to exterminate the house in the show.
Jorah never gets greyscale.
Lyanna Mormont is the youngest of five(?) daughters, not the only child of Maege Mormont. She is acting Lady of Bear Island but some of her sisters are still alive.
Sansa never leaves the Eyrie, never gets sent to Winterfell, never marries Ramsay, and never gets raped. She never escapes with Theon and she never makes it to the wall to meet with Jon. She is still with Littlefinger at the Vale. And none of those events will happen even after the books catch up with the show, because all those events happened to Sansa’s childhood friend, Jeyne Poole.
Cersei is an alcoholic sex addict who sleeps with both men and women. She cheats on Jaime very frequently, and when he finds out, he abandons her. This causes her to lose her mind and sees every one as a threat. She’s crazy.
As GRRM has said, the books are the books, and the show is the show. They have almost completely parted ways. Stop nitpicking what should be considered canon and not canon. As far as I’m concerned, anything not written by GRRM is not canon. The doesn’t make the show any less exciting to watch. Each episode cost 10-12 million dollars and each main character receives a salary of 1.1 million per episode. (Jon, Dany, Cersei, Tyrion, Jaime). They just simply don’t have the budget to create every little thing and make it 100% true to the books. Futhermore, D&D never signed up for finishing the story on their own. Winds of Winter was supposed to be out a while ago.
I also just want to point out: even Jon Connington has started to doubt that Young Griff is Aegon. “His eyes are a different shade of violet than Rhaegar’s” (or some quote like that). There is a lot of speculation that that boy is probably a Blackfyre (distant / bastard Targaryen).
Also also - I know they’ve never mentioned this on the show, so I don’t blame any show watchers for not knowing this, but Rhaegar was COMPLETELY obsessed with his prophecy of the prince that was promised and the song of ice and fire. His son absolutely had to be named Aegon. He was sure that his first Aegon with Elia would be the PTWP because a comet flew overhead the night he was conceived. Then he learned Elia was frail and another pregnancy would kill her, she could not give him the third head of the dragon, and that he was wrong about the first Aegon being the PTWP. So, in my opinion, assuming Rhaegar had no idea his first two children with Elia (Aegon and Rhaenys) would be murdered, he was expecting Lyanna to birth a girl, Visenya, the third head, and the final person to completely the original trio of Targaryens. But since Rhaegar died, and word probably reached Dorne that Elia and her children had been murdered, Lyanna knew (from assumed previous conversions with Rhaegar) that they boy HAD to be named Aegon. There was no way that Rhaegar, near mad with obsession over this prophecy, would have allowed or wanted Lyanna to name their son anything other than Aegon.