The Exorcist: Believer is a direct sequel to the original The Exorcist movie that borrows a lot from the 1973 classic, but there are a handful of key differences between the films. In a bid to spearhead a new Exorcist trilogy the same way he spearheaded a new Halloween trilogy, David Gordon Green directed and co-wrote The Exorcist: Believer as a way of reintroducing moviegoers to the Satanic thrills of this iconic franchise. The Exorcist: Believer brought back the revered stars of the original movie, Ellen Burstyn and Linda Blair, to reprise their roles in a new tale of demonic possession.

https://screenrant.com/exorcist-believer-original-sequel-differences/