Economics concerns itself with how scarce resources are allocated to satisfy people's wants and needs. In other words, Economics studies how people use resources that are ''rare'' to satisfy the unlimited wants and needs of people.
Business Studies on the other hand studies the function of a business and the decisions businesses make to ensure they make a profit and ultimately survive.
Generally speaking, Economics is more ''rigorous'' than Business Studies, and is also a much more prestigious subject to gain knowledge about.