hi,

m.arch is 2 years duration post graduate course which can be done after completing b.arch. a.arch and b.tech in architecture is similar disciplines and similar course in syllabus, however to become a licensed architect you need to complete 5 years b.arch course from a recognized university.  some of the south indian universities offer btech in architectural engineering which is a sub discipline of civil engineering, you may apply for mtech in structural engineering after completing btech in architectural engineering.