there are a few thinga to say on this
pc download speeds measured by speedtest.net are done with parallel downloads not a single download. This gives an unrealistic result unless you are going to use torrents or steam. Also speedtest steers you to in isp network or hyper local servers, which also help. But mainly, they flood download and upload channels with simultaneous requests.
the ps4 speed you might measure or observe is a single tcp stream and to a server at psn or otherwise that is probably more remote than whatever you test the pc against. The server might also be busy preloading bloodborne or whatever.
So apples to bananas make sure you compare the same thing: speed of a single download, to a server the same latency away! not psn game download speed to pc speedtest.net speed!
if you want to test a single download, pc vs ps4, try
http://www.dslreports.com/speedtest/simple
or there is also a multi stream download speedtest at
http://www.dslreports.com/speedtest
which will fill your comcast connectiom
however I dont know if the latter one works on the ps4 browser - which lacks more than a few features vs even phone browsers let alone desktop.
Lastly, the ps4 tcp stack may not be configured to be as aggressive as it might be. Normally, osx and linux scales a single tcp stream up a lot more than windows does but I dont know if ps4 bsd has been configured for fast downloads over 50ms+ connections.