The electron content distribution of the north and south polar ionosphere is analyzed from 2001 to the beginning of 2019 from the Global Ionospheric Maps of VTEC computed each 15 minutes by UPC-IonSAT with a tomographic-Kriging combined technique. We have found the VTEC footprint of features previously reported by different authors and with different techniques: tongues of ionization, trough and dawn-side drifting structure, flux transfer event, Theta-aurora VTEC observation at SP, and Storm enhanced density (SED) during major geomagnetic storms. Moreover, by means of an unsupervised clustering algorithm (Learning Vector Quantization), we have characterized the main features of the ionospheric electron content climatology, separately for the north and south poles. In particular a mean Tongue Of Ionization (TOI) behaviour over south polar ionosphere during 1345UT-1945UT, from November to February, i.e. in local spring and summer seasons, is confirmed in agreement with recent findings.