Is hemichordata same as protochordata ?? If no whats the difference ? if yes whats the difference between protochordataand vertebrata ?

Hemichordata is not same as protochordata as notochord is present in protochordata but absent in hemichordata.

Protochordata and vertebrata are sub-phylum of Chordata. There are so much difference in both as listed below.

In protochordata, notochord may or may not be present in all stages of life and also nor does it run through the entire length of body. For e.g. Herdmania and Amphioxus
In vertebrata, notochord is present in all stages of life and later also give rise to the vertebral column. For e.g. Amphibia, Reptilia