Imagine two people talking about politics, using rational arguments and philosophical theories, and suddenly a third one comes in and starts ranting about the same topic, but from a very subjective perspective.
Or else, someone posts a humorous, yet shallow picture on facebook, related to recent events, and someone else comments, but in a highly elaborated manner.
In general, a discussion could be led for example in an academic way, it could be pub talk, it could be over-emotionalised, childlike, silly, precocious, relaxed, it could be in the style of a BBC interview or a heated quarrel. I would call all these "discussion styles" in lack of a better term.
What is a word (or an expression) for changing the discussion style or conversation level in such a way? Or is there even a better word for "discussion style"? In particular, I'm looking for a technical term possibly used by linguists.
An example sentence for the first question might be "In facebook conversations between people of different educational levels, [?] are frequently observed.", and for the second question "Alice and Bob were discussing politics when suddenly Charlie came in and completely changed the [...]"
Note that I'm not looking for an idiom for changing the subject in a conversation. The subject should stay the same, only the way the conversation is led should change.
I am also not looking for a specific way how the discussion changed, like "escalation".