OK this is all guesswork but...
...rice crispies are much lighter than corn flakes so there'd be an awful lot more of them in 30g, thus a lot more calories. Does that make sense or am I being totally stupid?
As for the corn flakes/Frosties thing - I am baffled. You'll have to study the small print. How much sugar, etc.
The only thing I would say is your crisps are going to contain more 'lard' so the cereals are going to be healthier if nothing else.
