A comprehensive comparison between APOGEE and LAMOST: Radial Velocities
  and Atmospheric Stellar Parameters
  We undertake a critical and comprehensive comparison of the radial velocities
and the main stellar atmospheric parameters for stars in common between the
latest data releases from the APOGEE and the LAMOST surveys. There is a total
of 42,420 dwarfs/giants stars in common between the APOGEE DR14 - LAMOST DR3
stellar catalogs. A comparison between the RVs shows an offset of 4.54 $\pm$
0.03 km/s, with a dispersion of 5.8 km/s, in the sense that APOGEE RVs are
larger. We observe a small offset in the Teff of about 13 K, with a scatter of
155 K. Small offset in [Fe/H] of about 0.06 dex together with a scatter of 0.13
dex is also observed. We notice that the largest offset between the surveys
occurs in the surface gravities. Using only surface gravities in calibrated red
giants from APOGEE DR14, where there are 24,074 stars in common, a deviation of
0.14 dex is found with substantial scatter. There are 17,482 red giant stars in
common between APOGEE DR14 and those in LAMOST tied to APOGEE DR12 via the
Cannon. There is generally good agreement between the two data-sets. However,
we find dependencies of the differences of the stellar parameters on effective
temperature. For metal-rich stars, a different trend for the [Fe/H]
discrepancies is found. Surprisingly, we see no correlation between the
internal APOGEE DR14 - DR12 differences in Teff and those in DR14 - LAMOST tied
to DR12, where a correlation should be expected since LAMOST has been
calibrated to APOGEE DR12. We also find no correlation between the [Fe/H]
discrepancies, suggesting that LAMOST/Cannon is not well coupled to the APOGEE
DR12 stellar parameters scale. A [Fe/H] dependence between the stellar
parameters in APOGEE DR12 and those in DR14 is reported. We find a weak
correlation in the differences between APOGEE DR14 - DR12 and LAMOST on DR12
surface gravity for stars hotter than 4800 K and in the log g range between 2.0
and 2.8.
