Is there a difference between "eigenfunction" and "eigenstate"? They seem to be used interchangeably in texts, which is confusing. My guess is that an "eigenfunction" has an explicit representation/argument, e.g. in terms of position, $x$, whereas an "eigenstate" is abstract.
Thanks in advance for any clarification! :)
But then again, some texts violate this rule, so I'm prolly wrong...