What is a punishment?
Punishment by definition: the infliction or imposition of a penalty as retribution for an offence.
What the offence is can vary greatly among various relationships. This is where the subject can get a bit controversial. No two dynamics are the same so it's almost impossible to say what deserves punishment and what doesn't.
What is your philosophy about using punishment in D/s relationships?
I really don't like to need to give real punishments. I never set my sub up for failure and with Butterfly specifically I know if she breaks a rule or requires a punishment she feels so bad about it that the punishment itself is nothing compared to how bad she feels about needing it.
They are needed and I think for most rules and some tasks I find it helps if the punishment is known before hand. This is both a deterrent and provides stability.
As a sub do you enjoy receiving punishments?
I personally do not have much experience as a sub and haven't been punished before. I can't really give much insight here,
What is the difference between a punishment and a funishment
This is also an area that has a lot of different opinions. I think the majority of threads you find here asking for punishments are actually looking for funishments. A punishment should have a specific purpose and be for a specific reason, it should not be enjoyable, it should not be fun.
A funishment is a total different story, many people get aroused doing things in their dislikes or things they love to hate. Nothing wrong with that at all and I enjoy this type of play, but I don't think they should be mistaken for actual punishment. Everyone's mind works different ways to there are different ways to interpret this. I don't think any of them are wrong.