Just a little thought exercise for you:
Read the following English sentences and tell me if they are different....
1. I have a car.
2. I have a car.
3. I have a car.
Now read the following English sentences, stressing the bold part...
1. I have a car.
2. I have a car.
3. I have a car.
The sentences are all the same, yet with the use of stress they are now all different and each would strike your ear as very odd if used under the wrong set of circumstances.
Now.....ask yourself what sort of linguistic device the Japanese language would use to accomplish the same sort of thing.