One thing that is different is that (with the exception of Amazon Lockers) they basically don't exist if you don't live in San Francisco.
BufferBox is in Toronto as well.
Our goal is to bring Swapboxes close to people who need them and add some really cool technology to the process. One advantage our users see is that they are notified immediately via email / text when the package arrives and can pick it up on their own time. They're also not tied into a monthly plan since we dynamically allocated space. No keys, no hassle. Some people have already figured out solutions that work for them, we just feel that there's still a lot of pain points that are unaccounted for! Hope that sheds some light for you :)
They are generally accessible 24 hours a day. You don't have to be the person the package was sent to, just the person with the key code.
The UPS store I use is accessible 24 hours with a key and door code.
But you can't have your girlfriend sign for your package.
Odd, my brother picks up my packages for me since I have been out of state for a while.
My wife and my brother pickup my packages for me from my local UPS store where I have a mailbox. Don't even need a key; they both know the owner personally.