Answer: The order of gut development
Step-by-step explanation:
A protostome and a deuterostome can be differentiated from each on the basis of order of gut development.
In case of protostome spiral cleavage and determinate take place in which the development of mouth takes primarily and development of anus takes place secondarily.
A deuterostome radical and intermediate cleavage takes place in which development of anus takes place primarily and mouth takes place secondarily.