What's the difference?
Look at Example B. At around 0:11, you can see a heart shape form at the top of the rosetta, but then I raise the spout of the pitcher away from the surface and bury whatever nice heart would have been there, resulting in a spindly top.
In Example A, at around 0:12 as the rosetta is finished off, I keep the spout of the pitcher close to the surface, letting foam release onto the drink without having the flow of the milk sink it down beneath the top layer.
With practice, you can get a heart on the top of every rosetta your pour (if that's actually the look you want to go for). Cheers!