Yes, there's a big (HUGE) difference between sterilization and contraception. Not that I approve of freely dispensing contraception to teens without parental consent, but to call it "sterilization" seems like a typical media tactic to hyperinflate a story. Or could it be scottish terminology?
When you read that 400 girls were STERILIZED, you think "Good God, how can something like THAT happen?!". Then you realize that what they're really saying is that 400 girls were given birth control. It's still bad, but at least it's not permanent. Maybe it's just local terminology. Or someone's got a huge grudge against the pharmaceuticals industry.
I'm not an expert in the subject, but honestly, I don't think Norplant goes around sterilizing the 3rd world.