In reply to kjhhgt76:
A continuous assign statement is unidirectional. The flow of data is always from RHS to LHS of the assignment.
The same cannot be said about a port connection when both sides of the connection are nets.
module top;
wire a=1;
bot inst(.b(a));
initial begin
#1 $display("a: %b",a);
force inst.b = 0;
#5 $display("a: %b",a);
end
endmodule
module bot(input wire b);
initial begin
#1 $display("b: %b",b);
#5 $display("b: %b",b);
end
endmodule
The wires a and b get collapsed into a single net.