"This is my ball."
They have the same meaning, but a different structure.
Ini bolaku = This is my ball.
Bola ini punyaku = This ball is mine.
In the first sentence, "ini" is the subject of the sentence.
In the second sentence, "bola" is the the subject of the sentence.
There is a difference in emphasis.
Something like this :
Ini bolamu ? (Is this your ball?)
Ini bolaku. (This is my ball)
Bola ini punya siapa ? (Whose ball is this?)
Bola ini punyaku. (This ball is mine)
You dont need the word "adalah". I think you are trying to directly translate the word "is" with adalah. In this instance it doesn't quite fit right, though it would pass in a conversation.