Hello
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Let's first understand about BCOM  general and BCOM corporate secretaryship.
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B.com generals is all about commerce, accounting and economics.it's a  3 year's undergraduate course. You will have no depth information unless you are attempting 5th semester. Syllabus will not be that tough to understand. You can go it with little concentration.
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B.com corporate secretaryship, is all about company law's, secretarial practices. You will have a deeper information to study about the law's of the  company, laws that government implement on companies etc., Syllabus will be tough when compared to generals. It need a great concentration while getting prepared for examination.
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Now, if you want to go with accountancy/commerce and later with post graduation courses go for generals. If you don't have any post graduation Ideas and want to get a job after graduation then go with company secretaryship, as this Field has more job opportunities after graduation when compared to generals..step accordingly with your interest