Hello.
To put in simple terms, corpus luteum is nothing but the outer shell of the egg that has ruptured (at ovulation).
It secretes Leutinising harmone (
LH) , which the body further converts to HCg in case of pregnancy.
Luteal cyst is a type of follicular cyst.
On USG they look similar . CL cyst has coexisting pregnancy and increased blood flow.