On United, it's 1 million actual flight miles (does not count bonuses) on United metal that nets you lifetime Premier Executive status in United's Mileage Plus program.
That's roughly equal to American Airline's Platinum status.
American counts all bonus miles towards lifetime totals. United...only actual flight miles on them.
So while UA offers a better lifetime status level (one that offers 100% bonus miles, rather than just 50%) to it's 1 million milers, AA allows all miles to count towards towards million miler status, but you have to wait until 2 million miles to start to get the 100% bonus miles.
So it's kinda a wash competition wise.
[This message has been edited by PremEx (edited 03-05-2003).]