belong to と be動詞 + a member of のニュアンスの違い

ニュアンスの違い（微妙な意味の違い）ではなくて、はっきりと使っている言葉が異なります。それより細かい意味の違いはありません。回答しようとしても、ご質問の言葉を繰り返すことになってしまいます。

This is not a piece of advice to you I'm talking to myself for my practice of writing skills. I suppose each sentence has literal meaning. if these sentence have some nuances I suppose it would be exist together with some context of some contents. If these are sentences in a conversation I suppose it depend on situation/character/atmosphere/attitude of speaker/etc. I suppose I wouldn't decide how it is by only one sentence it'd be good also there are as many opinions as there are people.