There is a difference between mini-modding and being a helpful member. First off, a perfect given example of mini-modding would be "This is in the wrong section, you may want to try ___." Even saying, "Isn't this supposed to be in the ___?" These are all related to the occasional mini-modding dilemmas. It could be written rudely, and it could be written politely, but if it is off-topic from the thread (regardless of it needing to be closed, moved, etc.) it is still mini-modding and it is considered Off-topic/Spam. Which is why a member could be given a warning or infraction for doing it.
Now, while that is being a mini-mod, being a helpful member would more likely stick to the topic of the actual thread and at the end, give a helpful tip that this was actually supposed to be somewhere else or maybe it isn't allowed. However, the best thing to do when you think something is not in the right place or isn't allowed is to simply use the report button and report it. It may come off as a lousy way to be helpful in the sense, but trust me it works. I used to do it back when I was a regular member, and believe it or not, just by reporting something you may see can point out something to the moderator or higher staff that they did not see.
That's basically the difference between being a complete mini-mod and being a helpful member. And the reason why it isn't best to mini-mod other than it being considered Off-topic/Spam is because sometimes the member who mini-mods could give out the wrong information. This sadly, only gives the moderator double the work from what they were supposed to do the first time. :\
tl;dr, I know. :( ...But there is really no short way to explain it, if you want to really understand it.
