Astrophysical techniques have pioneered the discovery of neutrino mass properties. Currently, the known neutrino effects on the large-scale structure of the Universe are all global, and neutrino masses are constrained by attempting to disentangle the small neutrino contribution from the sum of all matter using precise theoretical models. We investigate an alternative approach: to detect the difference between the neutrinos and that of dark matter and baryons. Here, by using one of the largest N-body simulations yet, we discover the differential neutrino condensation effect: in regions of the Universe with different neutrino relative abundance (the local ratio of neutrino to cold dark matter density), halo properties are different and neutrino mass can be inferred. In 'neutrino-rich' regions, more neutrinos can be captured by massive halos compared with 'neutrino-poor' regions. This effect differentially skews the halo mass function and opens up the path to independent measurements of neutrino mass in current or future galaxy surveys.