Photos Confusion.

JS477

Unlike Android I've never been able to get my head around the way iOS handles Photos on it's various devices.

I've got an iMac an iPad and an iPhone.

According to my iMac when I open the Photos app and select Window--->Info I see that there are 1211 photos taking up 1.98GB of space.

When I plug my iPad into the iMac open iTunes and check the Summary I see that there are 1349 photos taking up 4.12GB of iPad space (see this)

However when I go to the iPad and select Settings

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>iCloud

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>Storage

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>Manage Storage---->iCloud Photos Library is showing that I "have 1,211 photos a 0 videos stored in iCloud. Your photos and videos are using 1.9GB" Using 1.9GB of space where?

Now the iPhone.

Plugging in the iPhone to the iMac that under Summary I see that the iPhone has 1384 photos and using 3.08GB of space (see this)

However going to Settings

---

>iCloud

---

>Storage

---

>Manage Storage---->iCloud Photos Library is showing that I "have 1,213 photos a 0 videos stored in iCloud. Your photos and videos are using 1.9GB" Again 1.9GB of space where?



Wha's confusing me is why is there such a discrepancy between iTunes and the actual devices as to what the actual storage is and which one is correct?

I have tried to understand the various Apple Support documents relating to iCloud/Photos but can't see where this issue is dealt with?