  Considering the delayed-choice quantum eraser using a Mach-Zehnder
interferometer with a nonsymmetric beam splitter, we explicitly demonstrate
that it shares exactly the same formal structure with the
Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) experiment. Therefore, the effect of
quantum erasure can be understood in terms of the standard EPR correlation.
Nevertheless, the quantum eraser still raises a conceptual issue beyond the
standard EPR paradox, if counterfactual reasoning is taken into account.
Furthermore, the quantum eraser experiments can be classified into two major
categories: the entanglement quantum eraser and the Scully-Dr\"uhl-type quantum
eraser. These two types are formally equivalent to each other, but conceptually
the latter presents a "mystery" more prominent than the former. In the
Scully-Dr\"uhl-type quantum eraser, the statement that the which-way
information can be influenced by the delayed-choice measurement is not purely a
consequence of counterfactual reasoning but bears some factual significance.
Accordingly, it makes good sense to say that the "record" of the which-way
information is "erased" if the potentiality to yield a conclusive outcome that
discriminates the record is eliminated by the delayed-choice measurement. We
also reconsider the quantum eraser in the many-worlds interpretation (MWI),
making clear the conceptual merits and demerits of the MWI.
