Both REMA and Assessment Area refer to geographic areas a financial institution serves. Understanding this geographic area is necessary when analyzing an institution's data for compliance, and evaluating performance compared to peers.
"REMA" stands for Reasonably Expected Market Area, sometimes shortened to just Market Area. It is used when discussing Fair Lending analysis, particularly Redlining. "Assessment Area" is used in CRA analysis.
To learn more, check out this recent blog.