Spoilers for Venom ahead. Every superhero needs a villain... even superheroes who aren't exactly superheroes. In the new movie Venom, that villain comes in the form of Carlton Drake (Riz Ahmed), who bonds with a symbiote named Riot (more on what the heck a symbiote is, below). But the Riot from Venom is far different from the one in the comics, and his connection to Drake is totally changed for the movie.
In the movie and in the comics, Carlton Drake is the head of the Life Foundation, which has a goal of providing a way for humans to survive in the event that the Earth is rendered uninhabitable. As pointed out by Comicbook.com, in the comics, this concern is related to the Cold War. In Venom, it's the environmental crisis. Drake isn't trying to help everyone, though. In the movie, this is shown through his willingness to do tests on homeless people knowing that it will likely result in their deaths.
So, first, lets talk about the Drake and Riot in Venom. The movie Drake is excited when the Life Foundation obtains several alien parasites, or symbiotes, from outer space. He believes that if the symbiotes can bond with a compatible host, this will allow humans to be able to survive on another planet. Of course, one of the symbiotes, named Venom, ends up bonding with Eddie Brock. Another one, though, ends up breaking free when the Life Foundation spaceship carrying the symbiotes crash lands in Malaysia. The symbiote makes his way to San Francisco — where Venom is — by attaching himself to a series of hosts of his own choosing. This symbiote is Riot, and in the movie he's basically the leader of the symbiotes and wants to bring a ton more of them back to take over the Earth. He also attaches himself to Drake and has a huge battle with Eddie/Venom.
Now, the Riot in the comics has a far different origin story from this; although he is still involved with the Life Foundation. Venom and his host Eddie were first introduced in the Amazing Spider-Man comics, and their story carried over to Venom specific series, including Venom: Lethal Protector. According to Comicbook.com, Riot was introduced in the Lethal Protector series. In the comics, Riot is an offspring of Venom created by the Life Foundation, along with four others, who are meant to provide security for the organization, as explained by Forbes. Riot initially bonds with a security guard named Trevor Cole, and is fought by both Venom and Spider-Man.
There are a couple of reasons for changing Riot's story so drastically for Venom. To start, it makes for a clearer story that can be told in two hours to have an evil symbiote bond with the evil head of the evil organization. Then, there's the matter of how these movies are being produced. Venom is based on a Marvel character, but it's made in association with Marvel Entertainment and distributed by Sony rather than being a part of the Marvel Cinematic Universe. Sony and Marvel Entertainment have an agreement that allows overlap of the use of Spider-Man, but Spider-Man is not a part of Venom. Basically, the movie not making any mention of Spider-Man limits what story it could tell from the comics and how directly it could do so.
In the end, the way Venom presents Riot is different than what fans of the comics are used to, but comic fans are surely already used to that happening when they see comic book-based movies. Plus, Venom leaves the door open for even more symbiotes to show up in the future should there ever be a sequel.