You may recall an article that revealed the Xbox One HDD would be full after installing 20 games in comparison to the PS4 which fills up after hitting 27 games. Both of the next gen consoles come with a standard 500GB HDD but the PS4 allows you to upgrade the HDD without voiding the warranty, and the Xbox One does not.
So to compare the two , the Sony machine allows you too use 407GB of the 500 GB hard drive meaning that 93GB is already allocated to things such as the operating system, whilst the Microsoft machine only allows 362GB out of the 500GB internal Hdd , that's a massive 148GB already used by the system.
Considering the size of Next Gen games the standard storage seems tiny in comparison. The great thing about the Playstation of course is that after downloading every single game that you can get on the PS4 and filling up the standard storage, you can of course upgrade to a bigger capacity Hard drive.
Microsoft have already confirmed that there will be an update to allow external storage and my guess is that Sony will also do the same even though you have the option to upgrade the storage capacity should you wish too.