basically everything in business is to do about how business's run, operate, employ, work, make cash, you get the point. economics is more about the economy and much more mathematical. you will look at ASX, shares, the government, just more boring. imo
You need to do quite a bit of rote learning for both subjects in learning definitions (you'll need to memorise much more for Eco because for business if you have a base knowledge of what you are talking about, can exercise common sense and know how to bullshit you should be fine) and Maths doesn't play as much of a role in HSC Economics as people think. (I remember I went into Eco thinking it would be quite mathematically heavy, the result was quite surprising)
You learn a lot of the business studies course in eco, but not vice versa. The economics course deals with things on a larger scale.
Also keep in mind the economics cohort is smaller (afaik).
I don't really agree with your first point. When I went through the courses although there were a few crossovers they tended to be minor.
The cohort of Business tends to consistently be 3x larger than the Eco cohort and the percentage of b6s attained in business last year was 8%, while eco was 12%. (take note that due to Eco's scaling you'd have a lot more academically strong people taking the course so this stat isn't too surprising)
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I personally enjoyed Business Studies more than Economics in terms of content since I found it really relatable to real life scenarios (like marketing via promotional strategies such as advertising and word of mouth, and just how businesses such as Maccas deal with their operational processes. I can't say I didn't enjoy Economics though, and I have definitely increased my knowledge of the economic world. Economics is much more heavy in terms of the amount you need to study but if you are willing to put in the effort it will be rewarding once you take into consideration the scaling benefits. IMO Business Studies is one of those subjects where if you are willing to work hard then you can achieve great results. Just to reiterate, I enjoyed Business more than Eco but both were enjoyable.
Maybe reading the headings for the HSC course and seeing which one you feel is more interesting would help since these topics are what will influence your hsc mark and ATAR.
Business Studies:
Generally for Business Studies, all topics follow a theme of analysing its role, what influences each part, the processes involved for that part, and the strategies undertaken for that part. The exception is HR which also has an effectiveness subtopic in the end.
Operations - Basically the process that businesses take to transform raw inputs into finished outputs (their products and services). If we were to give the example of Maccas the main part would be how they make your meal (it's obviously more complex than my example where you also learn about inventory management, quality management, how technological advancements affect these operations, etc). Along with marketing, I find this very interesting and these 2 topics are probably why Business was my favourite sub.
Marketing - The actions that a business takes in order to attain higher sales. This takes into consideration the pricing of the product/service, how it will be promoted (advertisements, discounts etc) and whatnot. You will also learn about the process of making a marketing plan (taking into consideration the business' situation, doing market research to identify customer needs, etc)
Finance - Name gives it away. Basically how a business controls their financial assets, what options they have in terms of borrowing and strategies to overcome financial situations (such as building working capital and managing cash flow). This topic is definitely more technical than the previous two though is still quite interesting.
Human Resources - Deals with employees. IMO easily the worst topic lol. If you are not banging your head against the wall while going through the legal influences of this topic out of boredom you are blessed.
Economics:
The global economy - Basically seeing the impact of globalisation on individual economies. You will also have a case study where you analyse the impact that globalisation has had on another country (nearly everyone goes with China) as well as strategies they undertake to promote eco growth and development as a result.
Australia's place in the global economy - How changes in the exchange rate, balance of payments and free trade and protection affect Australia's position in the global economy. Quite an interesting topic IMO though I think people would agree that the balance of payments (especially the CAD) is one of the harder concepts you will need to grasp. People also have difficulty in exchange rates.
Economic issues - As the name suggests, you learn about issues such as eco growth, unemployment, inflation, what causes them and what effects they have on the economy as well as how these issues have affected trends in the Australian economy. At first I really did not like this topic due to the sheer amount of information you need to learn (6 subtopics) but I find that after you learn it it is really rewarding and your general knowledge of economics increases.
Economic policies - The different types of economic policies. You will learn what they are, how they are applied, and how they affect the Australian economy. All you need to know is macro policies are heaps fun (fiscal and monetary), micro policies are not as fun (labour market and enviro policies drove me up the wall)