If you can simplify before distributing - and the PDFs you spam say you can - then there is no difference. You made it the fuck up.
2(n)^2^ is 2n^2^ whether n=a+b or n=a*b=ab. If you want to square the 2, that's (2n)^2^.
It's not about the multiply sign, or grouping, or division. You fooled yourself into saying 2=1.