Exactly. What are the "basic" Fighter, Cleric, Wizard, Thief, Dwarf, Elf, and Halfling? Based upon what the Head of the Class article seemed to indicate, they are the following:
Human Fighter (damage emphasis)
Human Cleric
Human Wizard
Human Thief
Dwarf Fighter (defense emphasis)
Elf Fighter/Wizard multiclass
Halfling Thief
...as if you actually used the "Races & Classes" module to build them, but just gave all the numbers out as unchangable or unmodifiable. The basic classes have been "pre-generated" for you.
And this is how you can put these Basic ones right next to "advanced" ones (ie ones that have been created using the Races & Classes module). They are all built with the same numbers and same mechanics, and thus are all balanced against each other and all playable with each other.
And in fact... two separate players could probably play a Dwarf (basic version) and a Dwarf Fighter (advanced version) and them be perfectly balanced with each other and look virtually the same after all was said and done depending on how the advanced one was built.