Norway is not neutral but a NATO ally. Austrai and Sweden are however considered neutral and was also an early UN member.

Switzerland's abstaining may seem even more odd considering that the European headquarters of the EU is in Geneva in Switzerland, as well as those of numerous UN agencies! (e.g. the WHO, WIPO, WTO in Geneva, the UPU in Berne) On the other hand, if the vote had been up to the Canton of Geneva alone, they would have been members long earlier.

The core of the matter is that while these countries are all labeled 'neutral', they have different ideas about what that constitutes. Sweden was neutral in both World Wars, and hasn't been in war for 200 years; a bit longer than Switerland. (although with fewer than 100 killed, the Swiss Civil War of 1846 was not so violent by war standards)

But Sweden has not been completely peaceful in the last 200 years (even if much more peaceful than the 300 years with dozens of wars before that) In the mid-19th century, Swedish troops were sent to give aid to Denmark in the First Schleswig war. At the turn of the century, Swedish troops were playing advisory roles in Persia, and a some Scandinavian mercenaries fought in the Boer War. The Swedish Navy briefly occupied the Åland Islands during the Finnish Civil War, and gave support to the Whites. A brigade of Swedish volunteers fought on the White side as well. Many volunteered for the Winter War of 1939 as well, although official support wasn't very strong.

Post-WWII, Sweden has been a quite active UN member (the Swede Dag Hammarskjöld being one of the most important Sec-Gens of the organization), and participated in many UN peacekeeping actions around the world. So has Austria and Finland.

So in short, Swedish neutrality has meant the country has been non-allied, and not fighting wars, but it hasn't meant a complete lack of military action abroad, much less a lack of opinion. During the Cold War and in particular under Olof Palme, Sweden made a name for itself for being quite vocal in international affairs.

Austria on the other hand, was a major player (as the Austro-Hungarian Empire) in WWI, and part of Nazi Germany in WWII. Its neutrality was to some extent foisted upon it by the Cold War parties. It has also been rather low-key in foreign policy matters, but it's not like Switzerland.

This is something very different from the stricter and perhaps one might say 'more conservative', Swiss idea of neutrality. Switzerland has followed a path of restraint, having a low-profile in foreign policy matters - in simplistic terms, keeping everyone happy with them - unlike Sweden who sometimes infuriated both sides in the Cold War. Switzerland had not sent troops abroad to nearly the same extent - although one rare Swiss-Swedish effort would be the handful of men in the Neutral Nations Supervisory Commission on the Korean DMZ.

The reluctance to send Swiss troops abroad was one of the main reasons for Swiss skepticism to joining the UN. And since, they have sent rather few; 31 to Afghanistan at it's height, while Sweden had 900, and Austria 60)

This carefulness and conservative approach isn't untypical for many things when it comes to Switzerland.