Although they can occur together, endometriosis and adenomyosis are two different things.
Endometriosis is when endometrial cells (the lining of the uterus) are in a location outside of the uterus.
Adenomyosis is when endometrial cells exist or grow into the uterine wall.
Although both can cause pain, endometriosis does not always cause heavy bleeding.
Reference
https://innovativegyn.com/learn-the-difference-between-adenomyosis-and-endometriosis/