in EK , what is the diffrent between CAT A Subload and CAT C Firm?
 

I do not understand the diffrent between the two type of tickets
are they both free ?
which is confirmed and which is conditional ?

Well the words 'subload' and 'firm' may be a clue... ;) and they are not free... confirmed tickets cost more, obviously

Another way to maybe understand it in other airline terms.... ID90 and ID50.

CAT A are akin to an ID90 (aka, cheap/lower priority)
CAT C if available are confirmed space tickets, or waitlist, akin to ID75 (more expensive)
CAT C Wider Eligibility are confirmed space tickets or waitlist, akin to ID50 (expensive)

Wouldn't it be awesome if we got 20 CAT A's to give away to Friends/Family like our friends operating out of OMAA do...

Best way I heard it described was:

Cat A: You're on until you're off

Cat C: You're off until you're on

K