How would you say "My blue book"?
Buku biru saya.
The word order in this English phrase (My blue book) is mirrored compared to the Indonesian word order.
ID phrase : The noun comes first, followed by the modifiers, the possessor comes last.
EN phrase : The possessor comes first, the noun comes last.
Buku biru saya = My blue book.
Celana merah saya. = My red trousers.
Mobil hitam saya = My black car.
But how would you say "the blue book is mine" then? Would it use some additional verb? Or is it totally undistinguishable in meaning in Indonesian*? That's something I'm getting really confused as I used to think about possessives as adjectives, but it looks like they don't work the same way in Indonesian. When - let's say - besar is at the end of the sentence, it means "is big", but if "saya" is at the end, it is translated as "my" not "is mine" and the whole thing is a noun phrase, not a full sentence.
*There were few times in this course where I translated this way and it was marked incorrect, so I doubt it (eg Dasi kuning saya - My yellow tie, I translated as The yellow tie is mine - incorrectly; yet considering "Ini punyaku" as "This is mine", the pattern is exactly the same, isn't it?)
But how would you say "the blue book is mine" then?
Buku biru itu milik saya = That/The blue book is mine.
Dasi kuning itu punya saya = That/The yellow tie is mine.
Indonesian doesn't have articles, so the definite article 'the' is translated into a determiner 'itu' (itu = that).
'milik saya' = 'punya saya' = 'kepunyaan saya' = 'my possession' (mine).
milik saya = milik aku = milikku.
I wonder, though, if the distinction you are stating is fully accurate. The Slavic languages are like this also. I think that we have to be careful about equating "this book" [buku ini] with "its/his/her/the book" [bukunya]. I'd welcome a native speaker with fluency in English to weigh in. Even between French and English, article usage is not the same.