- They are talking on the issue.
They are talking over the issue.
They felt concern over the matter.
- They felt concern on the matter.
I get to hear both types of sentences.please tell me difference between "on" and "over" in this context.
None of these phrases are natural as they stand. Here are some suggested alternatives, with Ngram graphs showing how much more common the alternatives are compared to the original versions.
They are talking about the issue - NGram
They are talking the issue over - no Ngram available
over is generally used in the phrasal verb talk sth over.
They were concerned about the issue - NGram