끓이다(kkeul-i-da, kkeulida)
To make water or liquid boil, focusing on the boiling process itself
When to use
Boiling water, Boiling broth, Making tea boil
The nuance
끓이다 means to bring a liquid to a boil, mainly used for boiling water or broth, focusing on the liquid boiling rather than cooking ingredients inside it.
삶다(sam-da, samda)
A cooking method where ingredients are boiled in water to cook through immersion
When to use
Boiling eggs, Boiling vegetables, Cooking ingredients in water
The nuance
삶다 means cooking ingredients by boiling them immersed in water, used when the ingredient is submerged and cooked, such as boiling eggs or vegetables.