As time goes on, old products get replaced by new ones, and then those old ones may not work anymore. When Apple declares their product "vintage", it means, that the device is now only eligible for repairs at Apple Stores and Apple Authorized Service Providers if parts remain available. "Obsolete", on the other hand, means that those devices are no longer eligible for service whatsoever.
Other definitions are, that a "vintage" device was last distributed by Apple for sale more than five years ago, while an "obsolete" device was last distributed by Apple for sale more than seven years ago.
Mac Rumors has noticed, that Apple has now added 3 more products to their lists.
MacBook Air (13", 2017) is now vintage, while iPad Mini 4 (2015) and Apple TV HD (32GB, 2015) are now obsolete.