the issue is entirely bound with the inadequate english terminology, over here it's always clear because you have ru and rosja, rusin and rosjanin etc. also the far better analogy are the dutch and the germans. danes are in a different sub-group of germanic languages, the dutch meanwhile exhibits relatively large degree of intelligibility with german, including a belt of what is surzhyk equivalent along the border, with the exception that the dutch generally know proper dutch while i've met multiple ukrainians(mostly from the centre of the country) who claimed western ukrainians speak mixed dialect.
Poland