Conference and journal papers in physics
I have seen, at various times, deliveries at conferences that discuss papers which:


have been published, 
papers that have been submitted and accepted for publication, 
papers that have been submitted and are in the review process, and 
papers which are still being prepared for submission (including papers which have not yet been written).


Sometimes a conference paper is also prepared and published as conference proceedings, as a summary, lead-in or discussion of preliminary results which are then published in detail in a journal.

It is expected that the paper submitted to the journal will be different enough to the conference paper to be suitable for publishing as a separate article without infringing on the "not submitted elsewhere" condition, and you will probably also need to either cite the conference paper or the journal paper in the other to avoid plagiarism.