気　气 and 氣 are actually not merged by han unification, and could be described as similar to similar to Ä and Æ: shared etymology, same meaning, some languages decided to use a simpler character because the old one was too complicated to write.

The variations on characters which have been merged are usually even closer than that. More like the single or double storey "a", or the single or double loop "g".

Well, maybe if the double-story "a" were used exclusively in one country but considered incorrect in another.

I think what you're missing is that Han unification never particularly concerned itself with whether characters are "the same" or not. Somebody basically just decided that some differences were important and others weren't. I mean, the difference between 語 and 语 is analogous to printing and cursive, but for whatever reason it made the cut. Meanwhile the SC and TC versions of 骨 are approximately mirror images, but to show you I'd need two different fonts.

Anyway the merged differences are not just analogous to different fonts.