Movie and miniseries have different approaches to creepy clowns.
It is already a smash horror hit, even outside the purview of Stephen King adaptations. The film grew out of the love for the miniseries starring Tim Curry as Pennywise, the evil that manifests most often as a clown, and the novel itself.
In the film, Bill Skarsgård plays Pennywise, to much more sinister effect. His is less charming, gruff uncle clown and more demonic weirdo clown. The aesthetics surrounding the clowns emphasize the shifted tones of the two adaptations, which Nelson Carvajal highlights in a side-by-side comparison.
This, along with his helpful narration, explains the shift in horror over the years as well as some creative theorizing about how different groups manage the same material. I’m more inclined to be positive towards the movie than Carvajal, but the video’s still a nice look at where horror visuals have traveled in the decades between the two Its.