As I see it, "very" focuses on the degree and extent of a certain quality. "so" is similar, but it has a directness and immediacy as if one is experiencing it right now. Because of this directness, "so" tends to have a greater impact than "very". For example, "I'm so sorry" or "I'm so sad" sounds more compelling than "I'm very sorry" or "I'm very sad". We might say "very" is about description while "so" is about direct experience.

"So" is more stronger than "Very".

Well actually "So" is used to express your emotion toward something in the moment. For example, you can actually see the different between these two: 1. "I am so happy." 2. "I am very happy." The first one sound more emotional towards feeling , while the second one sound a bit passive.

"so" is used in many ways but I think you are referring to this: e.g. You're very kind = You're so kind. "so" adds emphasis and warmth.

你的问题 有点类似问 ‘很’ 和‘非常’ 的差别 .....