The 'How Not to Summon a Demon' manga and anime are pretty close. Maybe there are a few differences in how certain scenes are depicted or in the order of events, but the essence of the story is intact. Fans usually enjoy both versions for their own merits.
Overall, the manga and anime of 'How Not to Summon a Demon' have a lot in common. However, the anime might have some changes in pacing or added visual effects to make it more engaging for viewers. The core story and character development remain largely the same.