Okay....

The ages at which people commonly die in developing countries is in a much larger range than the ages when people in established countries die.

or

While people in established countries usually live about the same amount of time, those in developing countries live widely differing amounts of time.

or

The expected lifespan of a person in an established country is much less variable than the expected lifespan of a person in a developing country.

or

It's more common for people in developing countries to drop dead at any time than it is for people in established countries.

Do you like any of those better?