I was thinking about the ABC program called The Conversation, and the implications of giving it that name rather than, for instance, The Interview. A conversation is a much more friendly affair and implies that both parties contribute. This differs from the interview where the person in control fires off questions and the interviewee supplies what information they have. The interviewer has the power to cut the interviewee off and intervene with more questions, whereas people engaged in a conversation are much more flexible and considerate of each other in setting the pace.
A dialogue does indicate there are two people and that they are both engaged in displaying their points of view and knowledge of the subject. It is rather more lofty than the conversation which, while in some settings quite upmarket, is nevertheless pretending to be informal and casual. A panel is a dialogue with more than two people. A forum is a free-for-all.
At the other end of the range we have talk, chat, and natter, all of which are much shorter and more informal. However, they can be graded in tone with the help of a strategic pointer. A short talk or a brief chat can be quite light-hearted, but a serious talk is deep and meaningful. Having a talk or a chat WITH someone is different from having a talk and a chat TO someone. In the latter case the point of it is to tell someone what they must do. While informal, it is by no means light-hearted.
A yarn involves some storytelling, however minimal. I might have a chat to my neighbour about the state of the garbage bins. If I have a yarn with my neighbour it is more likely that one of us is telling stories about our personal lives or the history of the neighbourhood, or the like.
The one I like best is chinwag. It has a visual appeal and a certain archness to it, as if it is sending up our human love of chatter.
It is not surprising really, given the subtleties of human communications, that we should have so many words and phrases with different connotations in the lexicon of verbal exchanges.