I am not absolutely sure I am comprehending your question correctly, but I believe you are asking if a child with developmental delays can display a wide range for language skills. The answer is yes. It is not unusual for receptive skills to be developed and therefore "test higher" than expressive skills. There are a variety of reasons, and without knowing details I cannot answer why.
Please feel free to go to the Association for Speech and Hearing website for more language based resources. http://www.asha.org