Was recently browsing photos of early Apollo missions and noticed that the plume of the Apollo 4 (source: ap4-67-HC-745.jpg) during launch is significantly bigger than that of Apollo 8 (source: ap8-KSC-68PC-315.jpg). Wondering why is that?

https://www.hq.nasa.gov/office/pao/History/alsj/a410/ap8-KSC-68PC-315.jpg Apollo 8 launch

https://www.hq.nasa.gov/office/pao/History/alsj/a410/ap4-67-HC-745HR.jpg Apollo 4 launch

I am not a hoaxer or something like that. I know for sure that people from the planet Earth walked on the Moon 6 times. The evidence to support that is overwhelming. Just really curious why such a difference. Does it depend on payload mass or different engine mode or something like that?