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The submissions feed will retrieve all type of submissions: submitted, saved, deleted (Deleted submissions are soft deleted meaning they are marked in the database as deleted, but the records are still present in your the DB and so they will be returned in your SubmissonFeedthe SubmissionFeed). The Submissions Submissions UI page, by design, shows only the submissions which are completed.
Let's say you want to sort submissions that are saved versus those that are submitted. You can use SubmissionEntry.getState() parameter. This will return the current state of that particular a SubmissionEntry (SAVED or SUBMITTED) and you . You can use this property to distinguish between your submissions.