We study the transversal structure (in particular the filamentation) and the longitudinal plasma stratification in two sets of solar coronal loops observed with TRACE in the 171 and 195 Å passbands. The density stratification and the thermal structuring of the plasma along the fibrils that form the loops are derived using two techniques simultaneously: (1) a filter ratio diagnostic (195/171 Å) and (2) modeling intensity profiles along the fibrils with hydrostatic models; in both techniques we remove the background flux. We find consistent values of temperature and density with both methods in the coronal structures selected. We find evidence of a very warm fibril (T~5×106 K) and of rather cold ones (T~2×105 K). The hot fibril appears to have a thermal structure with a maximum at the apex compatible with temperature and density stratification, dictated by energy balance, typical of a nonisothermal hydrostatic loop. The cold fibrils appear to be isothermal and are probably in dynamical conditions.