There are many different types of open access publishing models. When looking at the author requirements, please consult this list to understand the different formats:
Pre-print – a manuscript draft that has not yet been subject to formal peer review, distributed to receive early feedback on research from peers.
Post-print – a manuscript draft after it has been peer reviewed.
Version of Record (VOR) – the final version of a manuscript, after peer review and processing by a publishers.
Hybrid – a type of journal in which certain articles are made open access for typically a significantly higher price (relative to full OA journals), while others remain toll access.
Accepted author manuscript – the version of a manuscript that has been accepted by a publisher for publication.
Eprint – a digital version of a research document available online for a repository.
Green OA – making a version of the manuscript freely available in a repository.
Gold OA – making the final version of manuscript freely available immediately upon publication by the publisher.
Gratis OA – the paper is available to read free-of-charge, though its reuse is still restricted, for example by ‘All Rights Reserved’ copyright.
Libre OA – the paper is made available under an open licence, allowing it to be shared and reused, depending on which licence is used. (Libre and Gratis refer to copyright and licensing restrictions)
Diamond OA – a form of gold open access in which there is no author fee (APC).
This list is taken from the Open Access Academy website (included in this libguide).