General considations
Conference proceedings are typically short papers discussing preliminary findings or research in progress. Journals may choose to gather the ideas and results of conference proceedings in a special journal issue following the conference. When this happens, conference delegates are typically invited prior to the conference by the steering committee to submit their results to the special journal issue. Under these circumstances, your paper will automatically be published journal content and thus cannot be published elsewhere due to copyright restrictions from that journal.
Transitioning your work from a conference proceeding format to a journal paper format involves further research to complete the proposed findings, then rewriting the research to align with the type of research paper you wish to submit, i.e. standard article, review, forum, followed by formatting the paper to meet the specific guidelines for your target journal. Due to copyright laws, journals typically will not publish work that has previously been published elsewhere in any other format (see the ‘My paper is published already in my language in a local journal. Can I publish again internationally in English?’ section). Therefore, deciding whether your research idea should be presented as preliminary findings in a conference proceeding or as complete results as a journal article will determine the outlet for your research. Complete research journal papers are more common, more highly read and cited, and carry more weight than conference proceedings, so academics will more often choose to publish their work as a research paper.
Practical example for Life Sciences
Within the life sciences, academic, not-for-profit societies are sometimes associated with local journals and thus will administer special journal issues following the annual conference for their society. This allows conference delegates to publish their presented results in a special issue of a journal. This work has been pre-screened by the conference steering committee that determine which authors will present at the conference and thus which work will appear in the journal special issue. The advantage for authors is the publication process is often expedited, as the pre-screening is a preliminary peer review and the journal will expect tight turnaround times to have the issue ready for publication. An example of these circumstances is seen for the International Society for Ecological Modelling, which commissioned a journal special issue for Ecological Modelling entitled ‘Ecological Modelling Global Conference 2016: 20th Biennial International Society for Ecological Modelling Conference, 8–12 May 2016, Towson, Maryland, USA (https://www.journals.elsevier.com/ecological-modelling/call-for-papers/call-for-papers-for-special-issueecological-modelling-global). The journal specifies all the necessary styling and formatting guidelines for authors and the expected publication timeline for submitted papers.