The difference between : 日 vs 号 I was reading a conversation and came to these sentences :

爸爸 ：双十一是什么？
妈妈 ：就是11月11号的网上购物节，在网上买东西很便宜。

I was wondering why it's 号 instead of 日. I then checked it on the dictionary and found out that 号 can mean &quot;the day of the month&quot;.
I have looked for an answer but not sure whether or not what I found is correct. It's said that 日 is more formal than 号 and that 号 is used when you speak casually.
Is that true? And is there any more difference between both words?
Thank you.
You are correct, 日 is more formal than 号。
When chatting with someone, you would normally use 号 instead of 日，in this case, saying 日 feels a little bit weird.
But when you are writing a document, you would want to use 日 unless you are writing a transcript of people chatting with each other.