"I am not Tini."
Translation:Saya bukan Tini.
Bukan - Is used when negating from nouns and adverbs.
Tidak - Is used when negating verbs and adjectives.
My Indonesian friend says one is more formal than the other, but it doesn't matter much.
Aku is more informal than Saya. Same as Anda is more formal than Kamu IMHO
Something that really confuses me is that the formal version of 'you' (Anda) is spelled with a capital, but the formal version of 'I' (saya) isn't and instead it is the informal version (Aku) that is spelled with a capital... WHY!!??