Asylum-related returns relate to cases where there has been an asylum claim at some stage prior to the return. This will include asylum seekers whose asylum claims have been refused, and who have exhausted any rights of appeal, those returned under third country provisions, as well as those granted asylum/protection, but removed for other reasons (such as criminality).
The term 'deportations' refers to a legally-defined subset of returns which are enforced either following a criminal conviction or when it is judged that a person’s removal from the UK is conducive to the public good. Information on those deported is not separately available and therefore the published statistics refer to all enforced returns. https://www.gov.uk/government/collections/immigration-statistics-quarterly-release https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/910114/returns-summary-jun-2020-tables.xlsx