There are two main ways that any device connected to your network is identified, which is by its respective IP address and MAC address. The IP address (Internet Protocol) you will be dealing with is not a public i.e. internet-wide unique IP, but an IP address on your internal network also called a Local Area Network or LAN that your router assigns for every device on it.
A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Data sent through the internet, such as a web page or email, is in the form of data packets
Every device must have an address that is unique on the LAN to communicate with the router, whether you’re using that device to reach the internet or talk to other devices on the LAN. In most cases, routers assign LAN IP addresses dynamically, with different devices getting different IP addresses at different times, rather than statically i.e. giving the same device the same address every time. Generally, the router reserves a range of addresses and assigns the first address in the range to the first device that connects to it, then the second address to the second connecting device, and so on.
An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing.
MAC addresses are the other main designator that routers use, usually in conjunction with IPs, to tell connected devices apart. MAC has nothing to do with Apple products but, rather, refers to a device’s Media Access Control address. This is a hardware serial number that is built into the wireless card (or, more technically, network interface controller or NIC) of every device. As such, it almost never changes.
Depending on your router, you might also get information about a device’s hostname, or some other kind of identifying information. A hostname is a name a computer calls itself. This may be either deliberately chosen by the user or set automatically by the device operating system.
Another way that routers sometimes differentiate devices is by guessing and displaying the make and model of the device. How does it determine this? Manufacturers often reserve a range of the first three (of six) segments on a MAC address for their company, or even for particular models of NICs that they make, so that their NICs can easily be identified both within the company and publicly. This three-unit designator is called an Organizational Unique Identifier (OUI), and upon detecting a MAC, some routers will look up a table of known OUI blocks and assign the corresponding entry to a description of the device.