What's the difference between "My Contacts" and "All Contacts"?

Question

What's the difference between "My Contacts" and "All Contacts"?
I have no other account other then my iCloud account (from what I can tell), but "My Contacts" has a significantly smaller number of contacts then "All Contacts".
What's the difference?

Answer 1

Thanks for posting the screenshots, that's helpful.  I didn't realize that you were looking at your groups.
"All Contacts" include (as the name implies) all of your contacts.  Below that are any contact groups that you may have defined.  These would normally be such things as "Work", "Personal", "Doctors", etc.; any groups that you find useful to define.  These contain subsets of the "All Contacts" group.
At some point, perhaps inadvertently, you must have created a group called "My Contacts", or imported it to iCloud from your computer.  At the time this may have contained all of your contacts and would have had the same number of contacts as the "All Contacts" group.  Then over time you probably added 433 additional contacts that were never part of the original "My Contacts" group, resulting in an "All Contacts" group that contained 1465 contacts.
If you don't have any use for the "My Contacts" group, you can delete it by clicking on it on the left sidebar, click the gear icon on the lower left and choose Delete.  If you're concerned about doing this, you can make a backup of this group first by selecting it on the left sidebar, clicking on a single contact within the group, pressing Control-A to select them all (they should all be highlighted), then clicking the gear icon and choosing Export vCard.  This will create a .vcf file that can later be imported back to iCloud if you ever need to (by clicking the gear icon again and choosing Import vCard).