Others/Wight Vulnerabilities?

[warden]

Quick question on the vulnerabilities for Others and Wights. Others are listed as being vulnerable to Dragonglass, while Wights are vulnerable to fire. I was under the impression both were vulnerable to both. Is this a typo?

[Jasca]

Wights aren't vulnerable to obsidian; Samwell Tarly hit one wight with obsidian dagger, and it didn't do anything. However, wights are "highly flammable", as said in ice and fire wiki, and obsidian, "frozen fire" works against others. (I don't remember were others vulnerable to fire, however).

Good source for information about others and wights: http://awoiaf.westeros.org/index.php/Others