आप (Ap) or तुम (tum) in Hindi is तुम्ही (tumhI) or आपण (ApaN) in Marathi.
“तू” in Hindi is “तू” in Marathi as well.
But do understand the difference in their usage especially its social background.
In Hindi, by default you address anyone else with respect i.e call him “आप” or “तुम”. And only when you do not want to show respect or show a very friendly relation you will address that person as “तू”.
In Marathi, it is opposite. By default, you will address anyone with “तू”. It does not show disrespect at all. It is natural for a native Marathi speaker to address son, daughter, brother, sister, cousin, mother, grandmother, unknown person of same age etc. with “तू”.
So when you translate a sentence from Hindi to Marathi, do NOT always translate “आप” or “तुम” with “तुम्ही”. It might sound unnatural in Marathi. So think, how closely you are related with the person in front of you and then better to go for “तू”.
That is why in this blog, I have given examples using “तू” in Hindi. So a sentence using “आप” or “तुम” should be the first thought in Hindi using “तू” and then go for Marathi translation.
Only when you have to show respect explicitly, you will use “तुम्ही”. So generally father, grandfather, teacher, boss, unknown person, an elder person are addressed with “तुम्ही”.
At home/in family relationships whom to call तू/तुम्ही is decided by tradition of that family and it is personal choice. Nowadays in many families (including mine) children address their mother & father as “तू”.
Similarly, few Hindi people use “हम” instead of “मै”. e.g. instead of “मुझे चाहिये”,”मुझे जाना है” they will say “हमे चाहिये”, “हमे जाना है”.
“हम” in Hindi is “आम्ही” in Marathi.
“मै” in Hindi is “मी ” in Marathi.
But while speaking Marathi NEVER use “आम्ही” instead of “मी”. People will laugh at you. They will think you as boasting yourself.
In old times kings, landlords or very respected person, elder persons etc. used to call themselves as “आम्ही” instead of “मी”, like in Hindi. But nowadays nobody follows this practice. So it will look very odd. So NEVER use it. When talking about yourself use “मी”.