• aap (aap/aapka/aapki/aapke/aapse/aapko/aapne) shows respect(for elderly, by default) and is also formal
• tum (tum/tumhara/tumhari/tumhare/tumse/tumko/tumhe/tumne) is casual(for same or less aged) and shows affection too
• tu (tu/tera/teri/tere/tujhse/tujhko/tujhe/tune), which shows no respect at all and therefore used among close friends, with younger people or in anger

aap/tum/tu == you

• “aap kaise hain?” or “tum kaise ho?” or “tu kaisa hai?” => “how are you?“

aapka/aapki/aapke/tumhara/tumhari/tumhare/tera/teri/tere == your

• [these ‘ka/ke/ki’ are to show your relation to the object and are used according to the gender of object]
• “aapka/tumhara/tera bhai” => “your brother”
• “aapki/tumhari/teri maa” => “your mother”
• aapke/tumhare/tere is a tricky one and used when there are multiple things related to you or something related to you is being used as an object in the sentence. (This is not always true and therefore it can be used to differentiate between a learner and an experienced Hindi speaker.
  • “aapke log” => “your people”
  • “Main tumhare ghar jana chahta hun” => “I want to go to your house.”
  • “Main tumhara ghar dekhna chahta hun” => “I want to see your house.”

aapse/tumse/tujhse == from/with/to you and more…

[this ‘se’ is a bit more complex (not originally, just because of English) than it looks. So, to the examples]

• when it means “from you”
  • “Mujhe tumse mere paise lene hain” => “I want my money from you.”
  • “Main tumse door rahta hun” => “I live far from you”
• when it means “to you”
  • “Mujhe aapse baat karni hai” => “I need to talk to you.”
• when it means “with you”
  • “Mujhe aapse baat karni hai” => “I need to speak with you”
  • “Mujhe tumse pyar hai” => “I am in love with you”

[So basically this complexity is due to translation from English and it simply means “one has something to do with you” - a connection or attachment or separation…]

aapko/tumhe/tumko/tujhe/tujhko == to you

[it is rather simple and means you’re being treated as an object or being acted upon]

• “Main aapko marna chahta hun” => “I want to kill you” (not really :)
• “Kya tumhe football pasand hai?” => “Do you like football?”

[So ‘se’ and ‘ko’ are still confusing? Well. The verbs (kriya) in Hindi play an important role while deciding which one to use. It’s something that can be understood with more interaction with the language itself.]

> ‘aapka’ is ‘your’ but ‘aapko’ is not. ‘aapko’ is more like ‘to you’.

> ‘tumhe’ is ‘tumko’ and it shows that the sentence is all about you (personally) but you’re being acted upon

> ‘tumse’ shows a loose connection and ‘something to do with you’ and the verb seems to be more important here.

• You can not use ‘tumse’ in that sentence
• ‘tumse’ represents a connection (attachment and separation don’t matter) and therefore doesn’t always mean ‘from you’. Here it somewhat means ‘to you’ or just ‘you’