This article explains Smart Objects in Photoshop and tells the different types of smart objects & how to create, edit, and convert them.

When you select a file that contains layers created in Photoshop, the placed result comes in as an editable Smart Object.

Smart Filters Filters may also appear to be missing when using Smart Objects in Photoshop.

With the update, Lightroom files can also be opened as Smart Objects inside Photoshop. Smart Objects are layers that retain the original data in order to apply non-destructive edits, Adobe explains.

Adobe Photoshop CC has been updated with 3D printing capabilities, new perspective correction tools, and linked smart objects.