"Oversee" is something a boss(or project leader) does, they watch the work their subordinates (or peers who they have been asked to lead) do and make sure that everything gets done. "Overlook," is to miss something, like if you were looking for someone in a crowd but you thought they were further away so you looked over their head. So if someone who is supposed to oversee a project overlooks something, a crucial mistake in the project they are working on might happen.
Ohhh i see. I think i knew this but at the time it could not click in my head for some reason. Thank you for the explanation!!!















