The stomach works much harder to break down the fibre in whole fruit than in puréed or blended fruit meaning the sugars are released much more steadily. You feel satiated for longer and the 'sugar high/crash' effect is much less.
In terms of calorie consumption if you blend what you'd eat then there's obviously no difference but you're more likely to be reaching for something else soon after.
The programme that systema refers to didn't address the whole fruit/blended debate but the associated article does make interesting reading
www.bbc.co.uk/sn/humanbody/truthaboutfood/slim/soup.shtml