Difference between fetal ultrasound n level 2 ultrasound?

My doc asked for level 2 ultrasound but I had fetal ultrasound because she didn't write it on paper.now she is asking me to have level 2 ultrasound.i am not able to understand why she want level 2 ? I am not a high risk.everything came perfect in fetal ultrasound then y she's forcing me to have level 2? Just need an explanation that's all..may be I didn't went to the lab she recommended that's y she's asking me to go for level 2