It's a matter of convention. As you go up the chain away from more applied fields, you stop "designing" and "creating" things and start "discovering" that they

It's a matter of convention. As you go up the chain away from more applied fields, you stop "designing" and "creating" things and start "discovering" that they are possible. Mathematics and Physics are discovered, Chemistry uses both depending on the specific topic, pretty much all engineering is designed. A good way of thinking about it is considering intent. An engineer designing and then manufacturing a new car wants a to build a new car. A physicist making a new isotope just wants to prove that such an isotope can exist. In fact, often "discoveries" are can be purely mathematical: if you show a particle can exist in theory, that can be given a similar amount of weight as "proving" it by actually creating the particle.