For me,
Neupogen was significantly milder. As Linda pointed out, Neulasta is longer lasting,
Neupogen requires more shots. Neulasta is much more expensive, if that's a consideration. Even with the more frequent Neupogen, I found that that Neupogen at $400 each is a better bargain than Neulasta at $3000 each. (these amounts are based on what hematologist billed insurance, not my out of pocket). Your mileage may vary.