Now that PW got SpotPass, it’s time to add its counterpart: StreetPass.
StreetPass, just like the StreetPass on the 3DS, works by connecting to nearby devices. Those connections give you certain rewards and show you the PW accounts of those you connected to, so you can for example add them as friends.
Notification center is simple: It stores both SpotPass and StreetPass notifications. You get SpotPass notifications when the admins send you either a message or a gift, and StreetPass notifications when you connected to nearby devices.
Honestly, I don’t think Pixel Worlds is popular enough to utilise StreetPass to its fullest potential, it would be cool to see other, more popular apps implement something similar though.
They are both very different things, a ingame messaging system is very different from a “street pass”. Just because they added in one doesn’t mean they will add the other. I agree with other people on this thread it just isn’t worth the time to add. The game is way to small for this kind of feature.