At this time both are controlled by Cintra and are currently going under a several-years deep renovation process which will make them more attractive to sell. They are about to achieve it though. I definitely would not like to see them merger in one as they both have gained great reputation for service and safety and are doing okay by their own. Also, antitrust entities would not approve it.
I agree that they could build together a MAJOR group in Northamerica, nevertheless at this point they can do much more being by themselves.
About your last question; It is really difficult to compare one with the other; AM
is slightly bigger than MX
; both have differents markets being MX
the one that holds a bit larger slice of the US market. They both directly serve the US, Canada, Peru, Chile, Brazil, Argentina, Cuba, Guatemala, France, Spain, El Salvador, Costa Rica, Dominican Republic, Colombia and Venezuela. Service-wise it is known that AM
provides a better delivery on some routes.
About their fleet my friend Ghost77 will certainly give you more accurate information.
There are no stupid questions... just stupid people!