I checked some armybooks and found that most (checked a few) armylists where the company, detachment and special cards are listed sometimes go down in alphabetical order and sometimes not.
Example of no order: Adeptus Astartes Army Cards
Veteran Company
Terminator Company
Tactical Company
Assault Company
Devastator Company
Battle Company
Devastator Detachment
Scout Company
Land Raider Company
Bike Company
Example of order: Adeptus Mechanicus Army Cards
Castellan Detachment
Crusader Detachment
Errant Detachment
Lancer Detachment
Paladin Detachment
Warden Detachment
I believe that the differences are cases where there has been changes to the armylists. I do not know if this is in any way important but if I could choose I would prefer it in order. Unless its the chaos amrylist.

Comments please.
/Peter