I hate to use a car analogy but think about it like this:
The N96 gets better "miles per gallon" (or km per liter) compared to the
N95 /
N95 8GB
Your dad's old car has a 15 gallon tank but gets 15 mpg.
Your car has a 10 gallon tank but gets 40 mpg.
The tank might be smaller, but it goes farther.