I am new to V-AMS .

In the V-AMS LRm section  5.6.3 Resistor and conductor
We have following code for Conductance linear model.

module my_conductor(p,n);
inout p, n;
electrical p,n;
parameter real G=1;
branch (p,n) cond;
analog begin
I(cond) <+ G * V(cond);
end
endmodule

Why we call this as a model for linear conductance .As we have G as always fixed or as paramter.It looks like a current source model.

Also In place of
analog begin
--
end

If I replace it with analog block how does it make difference.
Thanks,

A current source would have I(branch) <+ iout; but as boe noted, this model's current is proportional to the voltage.

analog begin
...
end

is an analog block, so your second question doesn't make any sense.