Question for Xiaobaitu and others: fingerprinting and biometrics

Dear Xiao Bai Tu and friends:

My I-485 is pending. I have taken the fingerprinting four months ago, but yesterday I got a letter from USCIS which asked me for an appointment for biometrics. Is there any person here had the same experience for both fingerprinting and biometrics? What is the difference between fingerprinting and biometrics? Thank you very much!