It has been general cultural knowledge since the US developed and dropped nuclear weapons in Japan that nuclear weapons are different to others, and a war with two similarly armed nuclear arsenals would destroy much of the world and should be avoided at all costs.

My understanding is they are known to be exceptional for the following reasons:

1. They are exceptionally damaging, and do not decern for civilian life.
2. They can be fired from within defensive positions, from continents away from conflict
3. If one country fires, then (due to existing military alliances) all others will fire in response - destroying much of the world
4. Locations where nuclear weapons have been dropped are uninhabitable for years due to radiation

Below I suggest that, when comparing to conventional heavy weapons, these are not exceptional reasons.

They are exceptionally damaging, and do not decern for civilian life.

• There are many weapons that have no decern for civilian life (Eg Russia using chemical warfare in Syria in 2000s) See also the firebombing of japan (https://en.wikipedia.org/wiki/Bombing_of_Tokyo), FOAB (https://en.wikipedia.org/wiki/Father_of_All_Bombs), Dresden (https://en.wikipedia.org/wiki/Bombing_of_Dresden_in_World_War_II)
• If you want to destroy a city, it may take longer and use more weapons than dropping a nuke, but geo-politically there's not much difference between drop 1 nuke or dropping 1000 conventional bombs if the city and its inhabitance are wiped out either way.

They can be fired from within defensive positions, from continents away from conflict

• This is describing the vehicle for the bomb. You can attach other heavy weapons and have the similar capabilities (albeit as mentioned above, its not as efficient per weapon)

If one country fires, then (due to existing military alliances) all others will fire in response - destroying much of the world

• Similar to the use of chemical/biological weapons, just because one adversary uses them, it doesnt mean others will - because there are still international ethical, economic and political pressures that hold them against their use. Eg. If Russia dropped one on Kyiv, USA would not respond with another (I imagine they would respond with conventional inter-continental weapons or general military might and defeat them)

Locations where nuclear weapons have been dropped are uninhabitable for years due to radiation

• Levelled cities by conventional weapons are also uninhabitable for years (less years) until they're rebuilt. While having to abandon land due to conflict is terrible, the cost to rebuild could be spent to build a new city somewhere else.

So my question is, considering these points what else makes them exceptional? Or alternatively, how are these points invalid?

They are definitely more efficient per bomb, but I cannot believe pure damage/bomb is the only reason they completely define international geopolitics.