What are the differences between PEX expansion and crimp methods for plumbing installations?

PEX expansion method involves using a special tool to expand the PEX tubing and then inserting a fitting, creating a secure connection without the need for a crimp ring. Crimp method involves using a crimp ring and a crimping tool to secure the PEX tubing to a fitting. The main difference is the way the connection is made, with expansion method being considered more reliable and less prone to leaks compared to crimp method.