Let's say for example I have 2 pizzas.
I cut one into two halves and the other into eight eighths.
i'll take half from each pizza, meaning i have 1/2 slices of one and 4/8 slice of the other. the fraction with a lower denominator, in this case 1/2, has larger pieces because it is dived into less pieces than the fraction with a larger denominator.
One slice of the first pizza would be bigger than one slice from the second.
Hope this helped!