  Stars in the mass range from 8 to 10 solar masses are expected to produce one
of two types of supernovae (SNe), either electron-capture supernovae (ECSNe) or
core-collapse supernovae (CCSNe), depending on their previous evolution. Either
of the associated progenitors retain extended and massive hydrogen-rich
envelopes, the observables of these SNe are, therefore, expected to be similar.
In this study we explore the differences in these two types of SNe.
Specifically, we investigate three different progenitor models: a
solar-metallicity ECSN progenitor with an initial mass of 8.8 solar masses, a
zero-metallicity progenitor with 9.6 solar masses, and a solar-metallicity
progenitor with 9 solar masses, carrying out radiative transfer simulations for
these progenitors. We present the resulting light curves for these models. The
models exhibit very low photospheric velocity variations of about 2000 km/s,
therefore, this may serve as a convenient indicator of low-mass SNe. The ECSN
has very unique light curves in broad bands, especially the U band, and does
not resemble any currently observed SN. This ECSN progenitor being part of a
binary will lose its envelope for which reason the light curve becomes short
and undetectable. The SN from the 9.6 solar masses progenitor exhibits also
quite an unusual light curve, explained by the absence of metals in the initial
composition. The artificially iron polluted 9.6 solar masses model demonstrates
light curves closer to normal SNe IIP. The SN from the 9 solar masses
progenitor remains the best candidate for so-called low-luminosity SNe IIP like
SN 1999br and SN 2005cs.
