I think its just different isolated environments where you can test different things. we have a QA that has all the features of the next version. A pre prod that mirrors the prod for a week before a release and at least a week after.
And we have many dev and local instances of our apps.
The pre prod systems are used for patches and other security related updates. So is the QA if they systems guys want to test something before putting it even in pre prod (if they have 2 different ways to go and do not want to pollute the pre prod before knowing more).
Its more up to the people you work with to come up with 'jargon' that helps you all understand things easier and faster.
A firm can decide:-
Model -> what is prod/ pre prod
QA -> more bleeding edge, could have some features broken (especially if you do not have automated suites/ large junit/ selenium/ other test coverage) and some features wired differently then production or being planned for production.