which is why one is the 104 and the other 114?
In this case yes but, as you know, this is not always so. Manufacturer's numbers often run out of sequence. The DH.104 Dove was intended as a Rapide replacement. The first prototype, G-AGPJ, first flew at Hatfield on September 25, 1945, and featured twin De Havilland Gipsy Queen 71 (supercharged) engines (with 3-bladed props) and a retractable landing gear based on the Vampire fighter.
The original Heron, G-ALZL, flew on May 19, 1950 and featured four De Havilland Gipsy Queen 30 engines (unsupercharged with 2-bladed props) and a fixed undercarriage. This was the Series 1. The later Series 2 had retracting gear.
The Saunders Corporation of Canada converted several existing Heron airframes with 2 PT6A turboprops & other improvements which became the Saunders ST 27. They also built some from scratch as the ST 27B, later the ST 28.