Learn Japanese

I wondered the same thing. After searching a little, I found these two articles (multiple since I’m unsure and so wanted to cite my sources):

https://teamjapanese.com/japanese-punctuation/#niju-kagi-kakko-%E4%BA%8C%E9%87%8D%E9%89%A4%E6%8B%AC%E5%BC%A7-double-inverted-commas

https://www.fluentu.com/blog/japanese/japanese-punctuation/#toc_3

Both of which state that 『』are called 二重鉤括弧(にじゅうかぎかっこ) literally double hook brackets. And the normal ones 「」are called 鉤括弧(かぎかっこ) literally hook brackets.

They also state that 『』are typically used for quotes inside of other quotes.

Additionally, the Wikipedia article on Japanese typographical symbols says that they’re used for titles. (Under brackets and quotation marks, second item)

https://en.wikipedia.org/wiki/List_of_Japanese_typographic_symbols

Hope this helps! I learned a lot doing the research for it. The rest of the first two articles is really interesting to read too.