one is whether or not the coolant is highly pressurised relative to atmosphere, the other is what the thread was originally about, which is how reactivity changes with respect to temperature. this is the temperature coefficient of reactivity.

https://www.nrc.gov/reading-rm/basic-ref/glossary/moderator-...

the people you were responding to were referring to the latter. specifically, if a reactor becoming more reactive results in more or less total reactivity. this characteristic is related to, but independent of, how pressurized the coolant and/or moderator are.