Which unique address is a 128-bit address written in hexadecimal?

Every hexadecimal digit represents 4 bits, so the address has 128/4 = 32 digits.

A GUID (Globally Unique IDentifier) has 128 bits. They are usually written like this:

{38a52be4-9352-453e-af97-5c3b448652f0}.

There are different types of guids, depending on how they are generated. The first digit of the third group reveals the type. In the example above it is 4. A type 4 guid is fully random (except of course for the 4).