When right-clicking a linked (smart) object in the Layers palette, there are two options that seem to do the same thing:
What is the difference between these two functions?
How can I use a low-res placeholder and replace it correctly with a high-res image while retaining its dimonsions in the final photoshop file?
Replace contents replaces the internal contents of the Smart Object, embedding the content. No external file association is present. If the Smart Object is already a linked Smart Object, the association to the external file is broken and the external file contents are embedded in the Smart Object.
Relink to file changes the Smart Object from an embedded Smart Object to a linked Smart Object associated with an external file. If the Smart object is already a linked Smart Object, it merely changes the associated external file link. If you made changes to the external file outside of Photoshop, you'll need to use this option to update the Smart Object.
The primary difference is how the Smart Object is referenced, either embedded or linked. You won't notice a whole lot of difference within Photoshop itself, but you will notice a difference if you were to edit the contents/linked file of the Smart Object.
At least, that's my understanding. I'm not an Adobe dev though.
W and H percentages to 100%. It with then be proportional.. and you can further transform to resize if necessary.
If the Smart Object is already a linked Smart Object, the association to the external file is broken and the external file contents are embedded in the Smart Object.
This is incorrect. If the layer is already a linked S.O., when you replace content it will still be a linked S.O. So the difference is this:
Replace contents of Linked S.O. = Linked S.O.
Replace contents of Embedded S.O. = Embedded S.O.
Relink to file of Linked S.O. = Linked S.O.
Relink to file of Embedded S.O. = Linked S.O.
