From Science Europe Data Glossary
Definition: a digital repository is a place (data store) that holds digital resources, makes digital resources available to use, and organizes them in a logical manner.
Explanation: if the digital resources consist of research data sets, the narrower term data repository is preferred; if the digital resources consist of electronic publications of a single university or other research organisation, the term institutional repository is often used. A digital library is a near-synonym of a repository, but this is usually regarded as having more elaborate functions: a system that provides users access to large, organized repositories of knowledge or information. It not only provides users access to digital content in repositories but also provides tools to re-organize and enrich the content by annotating, building collections, and bookmarking.
References: http://esciencelibrary.umassmed.edu/thesaurus/data-repository; https://wikis.uit.tufts.edu/confluence/display/UITKnowledgebase/Digital+Libraries+and+Repositories
See also: trusted digital repository