发生这个词用来描述事情的发生或出现。比如，天气突然变冷可以这样说：今天天气发生了变化。
fāshēng zhè gè cí lái yòng lái bǐ sù shì qì tānɡ tūrán biàn lěnɡ kě yào zhōu yě shuō：jīntiān qìtānɡ fāshēnɡ le biànghuà。
The word 发生 is used to describe the occurrence or appearance of something. For example, you can say: Today's weather has changed.
发生常用于描述日常生活中的各种事件，如天气变化、事情发展等。
fāshēng cháng yòng lái bǐ sù shì qìtānɡ biànhuà、shìqíng fāzhǎn děng。
The word 发生 is commonly used to describe various events in daily life, such as weather changes and the development of things.
Both can mean something happens or comes up.
产生 is more about creating a result; 发生 is about something happening.