ATC: Makes and Models

I've downloaded a few aircraft from this site.....actually a bunch. One of the things I notice is that some seem to be more compatible with the built-in ATC than others. For example, the B-52 that I'm using will correctly identify as a "Boeing Stratofortress" if I request flight following in VFR. This shows me that the ATC probably has the word "Stratofortress" somewhere in its vocabulary, despite the B-52 not being a default user aircraft. However, for the L-39 that I use, ATC recognizes the model name (Albatros, with 1 "S") but not the manufactuer (Aero, or Aero Vochody. I've tried both). So how exactly does this work? Is there a vocabulary of manufacturers and types that go beyond the default aircraft, or is there just some software that tries to "sound out" the aircraft's name?