This could be a trivial question, but what is exactly the difference of between these two expressions? Am I correct to state the both interchangeably whenever I need to express the approximation of $\pi$? I'm bit confused as here, it states $\pi$ can be express by $\fallingdotseq$ as it's not a rational number, but $\pi$ can also be expressed by a series (asymptotic), so it should be $\approx$ as well.
$$\pi \approx 3.14\dots$$ $$\pi \fallingdotseq 3.14\dots$$