Do not try to compare networking to computer hardware. While in some cases this could help, it is comparing apples to oranges and clearly in this case it is causing some confusion. I think it may be best to just give a simple example to show how they are used differently.
Let's say your computer (192.168.10.1) wants to talk to a host (10.1.1.10). In this case, 10.1.1.10 is the logical destination or address you are attempting to send traffic.
Your computer however has no idea about the MAC or physical address of this server, nor does it know how to get to the logical address. However it does have a default gateway and knows 10.1.1.10 is not on the local subnet. So it sends the traffic to the gateway router with the logical destination of 10.1.1.10 and the physical destination of the gateway router's interface.
This router, will see that the logical address of the traffic is bound for another host, and will look up where it needs to send this traffic which indicates router2 is the next hop. It then changes the physical destination to router2's interface and forwards the traffic.
Router2 is directly connected to the server using IP address 10.1.1.10, so it changes the physical destination to the MAC address of the server and again forwards the traffic.
There can be number of additional routers on the path, but all through the process the logical destination address stays the same while the physical destination changes. This is also true for source logical/physical addresses along the route.
This document from Apple KB provides some background on Location scans.
It looks like that part of iOS is scanning for WiFi networks in the background and sending this data to Apple, enabling them to crowdsource a geo tagged map of WiFi access points to help with positioning accuracy in other apps.
EG: Your phone is at GPS co-ordinates Latitude:37.330558° and -122.029675° and reports to apple that it can see 8 wifi networks which it has discovered via the Location services scan. The phone then reports this data to Apple which it will compare to other devices data from the same area and, probably using signal strength data, will tri-laterate the AP location.
Why? So they can use the location of WiFi AP's to enhance positioning data so your apps/device can use that to send you useful data/ads/services.
Auto Join scans (I'm making an educated guess here) will be the scans that the device performs in order to discover commonly used and remembered networks eg; ClemensimHomeWiFi.
Basically it looks like Apple are extending the conditions when the device will use an obfuscated MAC address in these scans. Following the original release of this functionality in iOS8 it was discovered that randomisation only occurred under a VERY specific set of circumstances that most users would not enable/experience.
It has to use it's real mac address as soon as authentication occurs in order to maintain compatibility with WiFi standards that rely on mac filtering/auth.
As one of those people who is measuring foot traffic via the standard WiFi probes that Apple is altering this is an area of significant interest.
One thing is clear, Apple intend to aggressively pursue this path as a way to increase use of iBeacon and Apple services for advertisers wishing to reach consumers, it is NOT about user privacy. However, there is only so much they can do until the consequences start affecting performance on different WiFi networks and/or breaking the 802.11 specification.
Best Answer
Historically, both EUI-48 and MAC-48 were concatenations of a 24-bit OUI (Organizationally Unique Identifier) assigned by the IEEE and a 24-bit extension identifier assigned by the organization with that OUI assignment (NIC). The subtle difference between EUI-48 and MAC-48 was not well understood; as a result, the term MAC-48 is now obsolete and the term EUI-48 is used for both (but the terms “MAC” and “MAC address” are still used).
In other words, EUI-48 and the MAC number of a device represent the same thing! Usually it is represented in 12 hex (e.g. 0023.a34e.abc9), equivalent to 48 bits or 6 bytes.
By implementing the EUI-64 (64-bit Extended Unique Identifier format), a host can automatically assign itself a unique 64-bit IPv6 interface identifier without the need for manual configuration or DHCP. So it's an IPv6 matter. Anyway, if you are interested about how it's calculated, it is applied to a MAC address like this:
The 48-bit MAC address is split in half, the hex group
FFFEis inserted in the middle (after the 24th bit), and the seventh most-significant bit is inverted.Example:
MAC-Large, MAC-Small and MAC-Medium (abbreviated MA-L, MA-S and MA-M) have the all the same size. The names refer instead to number of bits within a MAC that remain governed by organization as opposed to the OUI bits governed by IEEE. If 24 bits of a MAC are governed by an organization/vendor/manufacturer, it is called a MAC-Large (this is a traditional scheme discussed so far). If 20 bits, it's MAC-Medium. If 12 bits, it's MAC-Small.
It addresses serious exhaustion problem of MAC addresses. Think how many devices are produced each day!