One is a consumer level - MC4 and has performance to match, the other, the pro DG is the pro TC, with performance to match!
They also do an MC7, which I have, which can be classed as the 'pro-Sumer" version.
In essence - MC4 - cheap but poor IQ and AF.
MC7- fairly good IQ with fairly good AF
PRO DG good IQ with reasonable AF!