[driverdan]

You're doing it wrong then. PNG8 is the same in both products. PNG24 isn't optimized in Adobe products. You need to run it through a PNG optimizer.

[joahua]

You're right that PNG optimizers will yield better results, but PNG8 isn't the same in both products.

Photoshop won't do 8 bit opacity (as opposed to hard transparency), whereas Fireworks will.