خوراك Refer to which food usually served without ric,or rowfood غذا Refer to cookedfood or each served meal during the day for example for dinner and lunch we use غذا Although it depends on sentences For example native persian say: غذا خوردم. Not خوراك خوردم

سلام به هر چی که بشه بخوری خوراک گفته میشه، مثلا علفی که حیوونا میخورن خوراک گفته میشه، غذا هم یه نوع خوراکه ولی نمیشه بگی که خوراک یه نوع غذا هست، بیشتر خوراک برای حیوانات به کار میره

They have some differences, but a quick answer for everyday Persian language would be: خوراک more formal ( usually is used in written language) غذا used by people in spoken language

they meaning the same. we have plenty of Arabic words using in Farsi. غذا is arabic.

khorak is a type of fast food, that is the only use of it I have seen. Don't use it instead of Qaza even if they both mean the same. more common form of Khorak is Khoraki which means the food children bring with them to school to eat it as a meal while they are there. Nobody use khorak as a word for food and meal in informal language! maybe it is useful in literature.