When is something a Deep Neural Network (DNN) and not NN?

When would a neural network be defined as a Deep Neural Network (DNN) and not a NN?

A DNN as I understand them are neural networks with many layers, and simple neural networks usually have fewer layer... but what a many and a few in numbers? or is there some other definition?

What are networks trained used Tensorflow, Caffee as such? I haven't (as far I know) seen anybody manually design a network with many many layers. They seem to promote their tools for creating DNN, but is it actually DNN if you only make a network with two layers?