  We compare the coronal magnetic energy and helicity of two solar active
regions (ARs), prolific in major eruptive (AR~11158) and confined (AR~12192)
flaring, and analyze the potential of deduced proxies to forecast upcoming
flares. Based on nonlinear force-free (NLFF) coronal magnetic field models with
a high degree of solenoidality, and applying three different computational
methods to investigate the coronal magnetic helicity, we are able to draw
conclusions with a high level of confidence. Based on real observations of two
solar ARs we checked trends regarding the potential eruptivity of the
active-region corona, as suggested earlier in works that were based on
numerical simulations, or solar observations. Our results support that the
ratio of current-carrying to total helicity, $|H_\mathrm{J}|/|H_\mathrm{V}|$,
shows a strong ability to indicate the eruptive potential of a solar AR.
However, $|H_\mathrm{J}|/|H_\mathrm{V}|$ seems not to be indicative for the
magnitude or type of an upcoming flare (confined or eruptive). Interpreted in
context with earlier observational studies, our findings furthermore support
that the total relative helicity normalized to the magnetic flux at the NLFF
model's lower boundary, $H_\mathrm{V}/\phi^2$, represents no indicator for the
eruptivity.
