Hi Anurag,
You can set the same permission for all workitem type, but you can not give different rights for different work item type directly.
Right click Project node in Team Explorer-> Team Project Setting-> Areas and Iterations->Security.
In the field definition, you can set "for" or "not" rule for different group/user, but it seems you need to modify many fields.
Best Regards,
Ruiz
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Sincerely,
Ruiz Yi