We compare broad emission line profiles and estimate line ratios for all major emission lines between Ly \alpha  and H \beta  in a sample of six quasars . The sources were chosen with two criteria in mind : the existence of high quality optical and UV spectra as well as the possibility to sample the spectroscopic diversity in the 4D Eigenvector 1 context ( 4DE1 ) . In the latter sense each source occupies a region ( bin ) in the FWHM ( H \beta ) vs. Fe ii _ { opt }  strength plane that is significantly different from the others . High S/N H \beta  emission line profiles are used as templates for modeling the other lines ( Ly \alpha , Civ \lambda 1549 , He ii \lambda 1640 , Al iii \lambda 1860 , Si iii ] \lambda 1892 , and Mg ii \lambda 2800 ) . We can adequately model all broad lines assuming the existence of three components distinguished by blueshifted , unshifted and redshifted centroids ( indicated as blue , broad and very broad component respectively ) . The broad component ( electron density n _ { e } \sim 10 ^ { 12 } cm ^ { -3 } ; ionization parameter U \sim 10 ^ { -2 } ; column density N _ { c } \ga 10 ^ { 23 } cm ^ { -2 } ) is present in almost all type-1 quasars and therefore corresponds most closely to the classical broad line emitting region ( the reverberating component ) . The bulk of Mg ii \lambda 2800 and Fe ii  emission also arises in this region . The blue component emission ( \log n _ { e } \sim 10 ; \log U \sim - 1 ; \log N _ { c } < 23 ) arises in less optically thick gas ; it is often thought to arise in an accretion disk wind . The least understood component involves the very broad component ( high ionization and large column density ) which is found in no more than half ( but almost all radio-loud ) type-1 quasars and luminous Seyfert nuclei . It is perhaps the most distinguishing characteristic of quasars with FWHM H \beta \ga 4000 km s ^ { -1 }  that belong to the so-called Population B of our 4DE1 space . Population A quasars ( FWHM H \beta \la 4000 km s ^ { -1 } ) are dominated by broad component emission in H \beta  and blue component emission in Civ \lambda 1549 and other high ionization lines . 4DE1 appears to be the most useful current context for revealing and unifying spectral diversity in type-1 quasars .