Presentperfect Continuous vs Present Perfect I can't find difference between Presentperfect Continuous vs Present Perfect and when should I use them

correction s a student in the faculty of Computer Science and Informatics; I had study not only computer science courses such as Programming Languages, Data structures and computer graphics, but also courses related to business as Economics and Feasibility Studies and courses related to management as management information system , Decision Support System and System Analysis and Design. I found a great passion on the courses related to management and get high scores in this courses. On my third year in the faculty I had to choose a major ,so I chose the major of InformationSystem and Decision Support System and for two years I had studied management information system, projects management ,executive information system and physiological risk in decision making .All these courses helped me improving my management, leadership, critical thinking and analytical skills. Few years, after my graduation, I joined as a volunteer on Google Business Group (GBG),it is a community of business professionals sharing knowledge about Google web technologies for business success, I got great experience in marketing and how to set online and offline marketing campaign, strategic planning, inspiring leadership and entrepreneurship.Drawn to my study and previous experience, therefore I want to get MBA degree and major of information systems and decision sciences (another term management information technology) Management information system is the study of people, technology, organizations and the relationships among them. MIS professionals help firms realize maximum benefit from investment in personnel,