Am I right in saying that the addition of G.Fast support is pretty much the only main difference between the 2865 & 2866?

2865
https://www.draytek.co.uk/products/business/vigor-2865-series#specifications

2866
https://www.draytek.co.uk/products/business/vigor-2866-series#specifications

That is the only difference. The routers are mostly identical except for the modem part, where the Vigor 2866 has the more advanced modem that can connect to G.fast as well as everything else.