Hello Daniel
Protected Extensible Authentication Protocol (PEAP) is a protocol that encapsulates the Extensible Authentication Protocol (EAP) within an encrypted and authenticated Transport Layer Security (TLS) tunnel.
EAP, which is the protocol that is encrypted, and protected by PEAP, is an authentication framework. It is a framework that leverages various types of authentication mechanisms, one of which is MS-CHAPv2.
Conversely, MS-CHAPv2 is a method of authentication, the actual mechanism by which authentication takes place. You can take a look at normal CHAP in action at the following lesson to find out more about how it works.
I hope this has been helpful!
Laz