In my experience, the difference between ‘article’ and ‘website’ is related to how Facebook uses the ‘like’. A ‘like’ of a page with type website will appear in the section of the user’s profile where it lists their likes; a ‘like’ of a page with type article does not. A user’s like of an ‘article’ object is more likely to be displayed to friends in their newsfeeds (although, as of now, even an article, without a comment, is pretty unlikely to make it into a newsfeed item, unless there are strong reasons– topic of mutual interest, very frequent interaction between the users– to make the item surface in Facebook’s algorithm).