Connective node means a node point which is related to other node no.

Like we model node 40 then node 50 then node 60 it makes continuous pipe.
Instead if I make 40 to 50 pipe then 50 connective node 51 with anchor then 51 to 60 another pipe . Both the above makes the same thing.

But If in connective node instead anchor we make Y support it will be different.

Connective node means there are two node no in same global co ordinate. Now we have choice to make relation between that two node no 50 & 51.

If we make connective node with Y support means there will not be any relative movement between them in Y direction but both the point are free to move with respect to other in Z ,X Ry,Rz & Rx direction