For common functions, icon metaphors are well known and used quite consistently across OSes. Example, cloud icon with down arrow to indicate that data is being downloaded from a server/cloud/online storage.
In this regard, The "+" icon metaphor has been used interchangeably for both create and add actions but when both actions are needed in a user interface, how can these actions be distinguished with distinct graphical/ icon metaphors?
Here I am considering:
Add action is including an existing object from the system
Create action is adding a new object to the system
As this is not a new problem and common problem, what add + create icon metaphor combinations have been successful based on products you have created/tested or used?