There is a difference because the two systems don’t overlap.
In the Apple Photos app, “All Photos” means all photos stored locally on that iPhone/iPad; and I think that can also include photos synced among your Apple devices using iCloud, if you have Photos sync turned on in iCloud.
In the Lightroom app, “All Photos” means all photos stored in Lightroom locally (but not Apple Photos), plus all photos synced through Lightroom Photos on Creative Cloud, which can include photos in Lightroom Classic enabled for syncing to Creative Cloud. It will not include Lightroom Classic photos that are not enabled for syncing.
The only time the two sets might look like they overlap is if you set the Lightroom app to automatically import photos taken by the device camera. When that option is on, the camera saves the photo to Apple Photos as it usually does, but Lightroom would then also make its own copy, and upload it through Creative Cloud.
That pretty much answers my question. I don't have LR auto import photos taken by device am set to ON. So it seems somewhere in the initial setup of LR mobile workflow to LR classic on my mac, I somehow managed to import photos I did not want to import into LR ipad. These were basically already completed photos that were in a folder in the apple photos app.