Ad hoc discussions have been gaining a growing amount of attention in scholarly discourse. But earlier research has raised doubts in comparability of ad hoc discussions in social media, as they are formed by unstable, affective, and hardly predictable issue publics. We have chosen inter-ethnic conflicts in the USA, Germany, France, and Russia (six cases altogether, from Ferguson riots to the attack against Charlie Hebdo) to see whether similar patterns are found in the discussion structure across countries, cases, and vocabulary sets. Choosing degree distribution as the structural proxy for differentiating discussion types, we show that exponents change in the same manner across cases if the discussion density changes, this being true for neutral vs. affective hashtags, as well as hashtags vs. hashtag conglomerates. This adds to our knowledge on comparability of ad hoc discussions online, as well as on structural differences between core and periphery in them.