  We present the analysis of $\sim 100$pc-scale compact radio continuum sources
detected in 63 local (Ultra) Luminous Infrared Galaxies (U/LIRGs; $L_{\rm IR}
\ge 10^{11} L_\odot$), using FWHM $\lesssim 0''.1 - 0''.2$ resolution 15 and 33
GHz observations with the Karl G. Jansky Very Large Array. We identify a total
of 133 compact radio sources with effective radii of 8 - 170pc, which are
classified into four main categories -- "AGN" (AGN), "AGN/SBnuc" (AGN-starburst
composite nucleus), "SBnuc" (starburst nucleus) and "SF" (star-forming clumps)
-- based on ancillary datasets and the literature. We find that "AGN" and
"AGN/SBnuc" more frequently occur in late-stage mergers and have up to 3 dex
higher 33 GHz luminosities and surface densities compared with "SBnuc" and
"SF", which may be attributed to extreme nuclear starburst and/or AGN activity
in the former. Star formation rates (SFRs) and surface densities ($\Sigma_{\rm
SFR}$) are measured for "SF" and "SBnuc" using both the total 33 GHz continuum
emission (SFR $\sim 0.14 - 13$ M$_\odot$ yr$^{-1}$, $\Sigma_{\rm SFR} \sim 13 -
1600$ M$_\odot$ yr$^{-1}$ kpc$^{-2}$) and the thermal free-free emission from
HII regions (median SFR$_{\rm th} \sim 0.4$ M$_\odot$ yr$^{-1}$, $\Sigma_{\rm
SFR_{th}} \sim 44$ M$_\odot$ yr$^{-1}$ kpc$^{-2}$). These values are 1 - 2 dex
higher than those measured for similar-sized clumps in nearby normal
(non-U/LIRGs). The latter also have much flatter median 15 - 33 GHz spectral
index ($\sim -0.08$) compared with "SBnuc" and "SF" ($\sim -0.46$), which may
reflect higher non-thermal contribution from supernovae and/or ISM densities in
local U/LIRGs that directly result from and/or lead to their extreme
star-forming activities on 100\,pc scales.
