Is there any difference between #define and # define?

Question

I'm studying C and, according to the style guide everyone in my school must abide, I should put a space between # and define, but never in #ifndef or #endif, for instance. If I do either, it says I have "bad preprocessor indentation". I was searching for the reason and couldn't find it, not even in the C99 ISO. In the ISO, by the way, there are 110 instances of #define and only 12 of # define, which makes me want to stick to the version with no spaces. But why would it be a bad style choice? If it's for indentation, why only a single space and not a tab or multiple spaces? Sorry if it's a dumb question. Thanks in advance!