[Help] Econcomics, GDP

I am having difficulty in understanding how these formulas and naming conventions work.
At times the term disposable income is used , or household income and then personal income. How do people tell the difference and is there any easy way to remember all these terms , like a standardized naming convention

Is this a new topic? Econcomics? Doesn’t sound like a subject I recall studying back in the good old Level 1 days… :laughing: