They’re different tiers, but economy is the majority chosen due to the price (business is expensive for most travelers hence why they opt for economy even if its crap) and it depends on how long the flight is rendering the price difference justified. If on a short flight, then economy is ideal if on a budget. However, if you’re heading somewhere it’s distant: business is better at the expense of paying a lot more than economy.
We’ve flown premium for and 3 years now after finding a seat sale where it was cheaper than economy. We loved the wider seats, increased legroom, and the food so much we’ve stayed at it.