Is there any real difference between these two sentences? I have found many internet pages where similar constructions are used interchangeably.
Both the sentences indicate the continuity of the action. The question started intriguing me a long time ago, and it still intrigues me. Look at a couple of examples:
I have lived here for years = I have been living here for years.
I have worked in this factory for years = I have been working in this factory for years.
However, in the sense of the continuity of an action, the present perfect continuous is preferable.
It has a difference:
“This question has been intriguing me for years” means that it started intriguing you at some point in the past and is still intriguing you!
“This question has intrigued me for years” means that you were intrigued in the past but not anymore!