Similarities – Threaded and pp compression fitting both use threads to help make their connections. However, they use the threads differently. Differences – Threaded fittings have a 1-piece connection end that is used to connect to port/block. These threads create the seal for the connection with the support of Teflon tape or pipe dope and are manufactured in a tapered, cone-shape. Whereas compression fittings have a 3-piece connection that is tasked with its connection to tubes. Compression ends typ