I didnt see much difference from novel to manga. The novel is just too wordy like spoonfeeding you the image he was to project. Wait for manga like Canaria said.
You are better off reading the novel from the beginning. They changed a few things which while are not that important to the story did make the story interesting. I was disappointed to see them skipped in the manhwa. Some scenes would've been more impactful if they had followed the novel imo. It's in the 60s(the dungeon visit) btw