What is the difference of 决定 and 决心？

决定 (jué​dìng):
决定 is a verb and is often translated as "to decide" or "to make a decision."
It is used when someone makes a choice or decides on a course of action.
Example:
他决定明天开始学中文。
(Tā juédìng míngtiān kāishǐ xué Zhōngwén.)
He decided to start learning Chinese tomorrow.




决心 (jué​xīn):
决心 is a noun and is often translated as "determination" or "resolve."
It refers to a strong and firm resolution or commitment to achieve a goal or overcome a difficulty.
Example:
她下定决心要减肥。
(Tā xià dìng juéxīn yào jiǎnféi.)
She has resolved to lose weight.