The definitions I’ve stumbled across seem to indicate they express the same idea. That’s that the relationship between record types is determined by their fields (or properties) rather than their names. Their Wikipedia pages also seem to indicate the same idea:
A structural type system (or property-based type system) is a major class of type system in which type compatibility and equivalence are determined by the type’s actual structure or definition and not by other characteristics such as its name or place of declaration.
In programming language type theory, row polymorphism is a kind of polymorphism that allows one to write programs that are polymorphic on record field types (also known as rows, hence row polymorphism).
Are there any differences between them?