Basically the same. I either buy PSN cards from pcgamesupply.com or I buy Amazon gift cards and use those to buy PSN. That is the same as I do for XBL credit.
Main differences between Xbox one and PS4:
- Xbox one: you keep the same account, but you change the region.
Pro: games from US store are still tied to your main XBL gamertag, so if you use a second console and sign in, you can still play those games.
Con: if buying brought the console you have to change region and reset the Xbox each time - and then again when you switch back. Also for me at least, when I do that it loses my DVR settings so I have to redo those. Not a maor hassle, but not perfect.
-PS4: you use a separate US account for purchases
pro: once you have a US PSN account added to your PS4, it is easy to switch to that account and go to the store, and then switch back to your normal account. No resetting etc. you can still play games on your usual account because you'll set the PS4 as primary console for the U.S. account.
Con: you can't play games on a second console using your normal PSN account - you need to be signed in with the purchasing account which is the US one.