Dear Dr. Alfonso

I am conducting an analysis of tMRI and want to convert activation and deactivation clusters to masks to create ROI for DTI tractogaphy seed purpose. My sample had two different types of z maps. One is created by conn toolbox (first figure) which is I assume is a Pearson normalized z-transformation score (please correct me if I am wrong), and the other was created through FSL through the process of randomize command --> TtoZ command available online on Neurovault.org (second figure). 
First question, how are those two maps are different in regard to the results because I can notice that the activation map has a bit of dissimilarities?
Second question, for the purpose of producing an ROI for DTI-tractography, which is the best one to use?

Best regards

Mudathir