Turbo question - what's the difference between a T3/T4?

my impression of the sizing is like large automobiles

the larger the turbo the larger the car would be ( stay with me) it takes longer to spool the turbo ( get the car moving) but say at the same speed ( psi for the turbo) the larger turbo / car would have more energy... such as a t25 working 10psi might make 200whp, while a t3/t04e 60 trim like mine might make 300whp @ 10psi...... although the t25 would probly make the 200whp about 1,800rpm's before mine ( reference to moving a larger turbo or larer car) i still preferr the suspense in waiting for it, and having more than a smaller one....