Another big difference is that ABT's repertory is focused on full-length story ballets, while NYCB usually performs several, shorter ballets each night.
Actually, 4 out of 20 (not counting the two guests) ABT principal dancers are American.
At NYCB, 6 out of the 22 principal dancers are foreign, though both Benjamin Millepied and Nilas Martins received a good chunk of their training at SAB. (Only Sylve, Marcovici,Tewsley and Hübbe were trained entirely at other schools - and Hübbe may well have been taught at some point or another by a past /present NYCB dancer while at the RDB School).
Out of the NYCB soloists and corps, I believe that only Ask laCour, Joaquin de Luz and Saskia Beskow did not spend any time at SAB, though laCour was taught by former NYCB dancers like Adam Luders and Colleen Neary at the RDB School.
Ethan Stiefel was at NYCB for many years - he was a principal dancer at NYCB before departing for ABT. Herman Cornejo was briefly at SAB, and Paloma Herrera was in the SAB Workshop one year.
Monique Meunier and Anna Licecia both danced with NYCB, and Eric Otto was a NYCB apprentice. Other SAB Workshop alums in the company include Arron Scott, Alexandre Hammoudi, Tobin Eason, Natalia Boesch, Eric Underwood, Grant DeLong, Anne Milewski and Ethan Brown.
A vast majority of the 03-04 Studio Company also spent some time at SAB including those mentioned above, Abigail Simon, Ana Sophia Scheller (now with NYCB), Lara Bossen and Melanie Hamrick.
ABT has started a small after-school training program, but it has yet to be seen whether this will sustain itself and/or grow. The company did indeed have a school early on and again while Baryshnikov was AD, but neither survived long-term.