They're basically at the same level if you don't use high end CPUs and gaming GPUs. Also see here: http://www.extremetech.com/extreme/135719-5-9-watts-the-worl... - tldr: 30w idle for an unmodified average system.
Mind you this was 2012, mid range systems surely haven't gotten more power hungry since then.
That's an order of magnitude more than an idle laptop.
And they're not talking about any sort of "average system" they're ballparking a "reference desktop" which tops out at 150W under load, that's not just "don't use a gaming GPU" that's "don't use a GPU at all". And if you're building a "desktop computer" with an APU and an SSD… why are you building a desktop computer?
