what does endometrial-like tissue even mean?

Hi all,

just wondering if anyone has found any cool links or articles on the characteristics of the tissue that grows outside of its normal range during endometriosis. is it endometrial cells, endometrial-like cells, or is it a mix of both?

but i can't find understand the difference between endometrial and endometrial-like tissue is. is the difference just their origin - aka what cell type they came from? or is it function - aka 2 different cell types with similar glands/stoma/growth pattern?

im interested to see who else has been curious about this, or has found any info in papers. thanks in advance!