Difference between PIC18F4431-I/P and -E/P

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This must be so obvious it is impossible to find .... what is the difference between PIC18F4431-I/P and PIC18F4431-E/P ?

Andrew

Edit:
Is it as simple as ?

"I means industrial temperature range, and E means extended temperature range" ?

Sometimes the packaging material is better, ceramic vs plastic, sometimes they are baked and checked to see if they survived, others irradiated and checked esp mil spec parts. I really think the silicon is the same.