ö in Icelandic and Swedish is phonetically equivalent to ø in Danish and Norwegian.
However the æ in Danish and Norwegian is like the OE one described in the article, between a and e, which is written ä in Swedish. Icelandic does not have that sound, and uses æ in the Latin way, representing the ai diphthong (as in English "fine").
The more common vowels also have fairly different pronunciations in the four languages.
