A 7 year old girl started learning Mishna in her (Jewish religious) school. Coming home from school her mother asked her about what she was learning, and she briefly discussed the (initial easy) Mishnayos she was being taught.
Her 5 year old brother overheard, came over and asked his 7 year old sister, “what’s Mishna?”
She answered “stories from Chazal” (stories from our sages).
He then asked “so what’s Gemora?”
She answered “complicated stories from Chazal”.
(Mishna is the foundational books of Jewish religious law, also known as the Oral Torah. Gemora is the Talmud, which starts with a statement from the Mishna and then goes into an in depth discussion, explanation, and contrarian positions on it – as well as associated (and sometimes not so associated) stories relating to it.)