Files only were migrated to Revel from Photoshop.com, not Elements. If you had your Elements organizer configured to auto sync with Photoshop.com and it was fully synced at the time of migration, then the accounts should match (minus duplicates and non jpg files). If you did not, don't worry, you can still upload the others to Revel from your hard drive. (or you can upgrade to Elements 11, which has an interface to Revel). See FAQ: FAQ: How do I add (upload) files to Revel? http://forums.adobe.com/thread/1162795?tstart=0
You had 580 photos in Photoshop.com at the time of migration. Your jpg files were migrated and you have 564 in Revel. The others likely were either non-jpg files or duplicates.
Does that clear things up?