I’ve learned that both mean something like “I see” or “I understand” but are
they interchangeable? Is there any difference?
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2019-07-03T18:22:34.537
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2019-07-08T23:09:15.207
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word-choice nuances
Different nuances of そっか and なるほど？
if you add question mark after なるほど, it means “I can’t understand what you’re
saying ” or “I can’t agree with you”.  

そっか and なるほど is very similar. I think the difference is that そっか is casual
response to others but なるほど can be use in both casual and formal situation.  
I think なるほど emphasis the point that “ I understand what you are saying”.  
otherwise I think そっか is more right response like “okay”.
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2019-07-06T19:07:24.457
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2019-07-06T19:07:24.457
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* そっか is very casual, and it's clearly inappropriate in formal settings. On the other hand, なるほど is safe in business exchanges, but it can sound a little pompous. If a small kid said なるほど, it would sound funny.
  * Both なるほど and そっか are used like "Aha, I (finally) got it!", but I feel そっか is mainly used when you have realized a bad thing, e.g., "Oooh, so I was wrong...".
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2019-07-08T23:09:15.207
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2019-07-08T23:09:15.207
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