I am confused on the differences between Usake Usaka Iskee and Iskaa. They all seem the same to me, and I can't tell the differences. I'm not sure what they mean.

Thanks!

Deven

Hi Deven,
Sorry for late reply. I was under impression that I subscribed to forums and I will get an email notification about any new question. I will have to check it out again. 

Here is your answer:

Usaka - singular masculine ( usaka kamara-- his room)
Usake - Plural masculine ( usake kapare - his clothes) , usake can be used as respectful masculine in singular case also. 
Iskaa - masculine, same as usaka but used when the person is present there. ( Is ladke kaa naam kya hai? -- What is the name of this boy?) 
Iskee - feminine (use is same as iskaa) (iskee choodi - This girl's bangle,  girl/woman is implied there by the use of iskee)

Hope this helps,
Gaurav

Hello,

The correct spellings of these words are: uske -उसके, uskaa -उसका, iski -इसकी and iskaa-इसका.
 
Usage and meaning
 
Uske is used as a reference point.
The following example will make it clear.
‘I am going to his house. मै उसके घर जा रहा हूं ।
 
Uskaa is used as a relative pronoun.
The following example will make it clear.
His name is John. उसका नाम जॉन है ।

Iski is also used as a pronoun. It is used with nouns which have a feminine gender.
The following example will make it clear.
Listen to her. इसकी बात सुनो ।
 
Iskaa is also used as a pronoun. It is used with nouns which have a male gender.
The following example will make it clear.
 His house is there. इसका घर वहाँ है । 

Hope it adds value.
Sudhanshu

Thank you Gaurav and Sudhanshu for your feedback!

Although, I am still confused on why you can't say मैं उसका घर जा रहा हूँ or उसका घर वहाँ है 

नमस्ते
 

Hi Deven,

मैं उसके घर जा रहा हूँ।  I am going to his house.
to his house is a dative/oblique case उसका becomes उसके.
घर remains the same in subjective, objective and oblique cases,

Let see another example: मैं उसके कमरे  जा रहा हूँ। I am going to his room.
 उसका  कमरा becomes उसके कमरे(oblique/dative case) to his room.

Let's wait for Sudhanshu's comment.

Hi John/Deven,

There are two example given by Deven - मैं उसका घर जा रहा हूँ or उसका घर वहाँ है   

1. उसका घर वहाँ है । is a correct statement
2. मैं उसका घर जा रहा हूँ should be मैं उसके घर जा रहा हूँ। as explained by John and correct. It is Dative case  (part of Hindi Kaarak (कारक)) as hinted by John. 

Kaarak (कारक) are the words which are commonly used before a noun, noun phrase, pronoun or verb. Also, connects with the noun, pronouns and phrases to other words in a sentence in order to make the sentence comprehensible for readers.

One of the part of कारक is Sabandh karak (संबंध कारक) - Dative Case. When an object is transferred to someone or for someone, the receiver of the object will be in the dative case.

Here are some examples:
I gave him the ball : मैंने उसको गेंद दी।
You brought gift for me: आप मेरे लिए उपहार लाए।
Harish sings for you : हरीश आपके लिए गाता है।
We gave them a letter : हमने उसको पत्र दिया।

In the sentences above, को = to के लिए = for.

Hope it will help
Regards
 

Hi John
Your example  मैं उसके कमरे  जा रहा हूँ। should be 

मैं उसके कमरे में जा रहा हूँ।