Most services consider a release to be a "single" if it contains 1-3 tracks, that are each less than 10 minutes.
If you upload an album with 1-3 songs, most major services will automatically add the "- Single" notation to the end of the album title.
In general, services consider a release to be an "EP, when it has:
4-6 tracks with a total running time of 30-minutes or less.
1 to 3 tracks, with one track at least 10-minutes long, and a total running time of 30-minutes or less.
Anything with 7+ tracks will be categorized as an "Album" within services.