In ArcGIS Pro, I recall the term feature layer being a wrapper for a single feature class only.
I'm new to AGOL. It seems like an AGOL feature layer is a grouping of multiple layers (AGOL layers being the equivalent of Pro feature classes or feature layers).
Is the above correct? Are feature layers different in Pro vs ArcGIS Online?
AGOL screenshot:

Related: Should I add the feature layer or it's sublayer to the web map?