The Hue device bridges LAN communication and Zigbee light link. Other devices like the SmartThings hub or the Staples connect hub or Logitech Harmony or echo talk to the Hue bridge via LAN. Then the Hue bridge issues the ZLL commands to the individual Hue bulbs. (While technically possible to connect an individual Hue bulb directly to the smartthings hub without using the Hue bridge, that is not the officially supported method.)
The Osram Lightify Gateway sounds like it would do the same thing, but until recently, it didn’t. There was no way for the SmartThings hub to talk to the Lightify Gateway. However, the individual Osram lightify bulbs could be connected directly to the smartthings hub through an official integration.
So officially, the SmartThings integration with Hue is through the bridge, and the official integration with Osram is direct connection to the individual bulb.
Osram Very recently released an open API to allow third party connection to the gateway, but I don’t think anyone has actually tried the gateway integration yet with SmartThings.