Mariah had the effortless power and same fullness to her voice whether belting in the 3rd octave or the 6th octave. Her vocal acrobatics was second to none, weaving up and down the scale while showcase perfect vocal technique.
Whitney had perfect pitch and accuracy when going for notes. Her belting and resonating >
But! Whitney was a better performer and commanded attention when on stage, while Mariah was always the better vocalist imo.
Both are the benchmark for modern day vocalist. Mariah's voice was always more versatile,not only that but her flexibility in her upper range is leagues above Whitney's abilities. Whitney's bread and butter was her mid chest belts.They were full and resonant. She also belted straight from the mask.Her timbre was so heavy and dark,yet somehow light and tranquil when she wanted. Though Mariah's perfectly pitched mid register was sonically jaw dropping too.So to me they were equal in that category. As far as head voice.. Sorry fellow Lamby pals,but Whitney >>>>>>>>>>>>>
I always found the tone of Whitney's head voice sweeter.Very operatic too in the way she executes it.
Though Mariah's falsetto is much softer and ethereal,and it's kinda one of her trademarks.(and yes there is a difference between head voice and falsetto)
As far as the lower register goes,Mariah's lower notes sound more solid and full.I believe her lower range is bit more extensive than Nippy's.
Mariah excelled overall. A lot of people always says Whitney had the power,and Mimi had the range,but IMO Mariah slayed in both department synonymously.
Also her use of melisma was much more creative. Mariah was much more dynamic. Mariah's melodies are very artistically unique,and you can't help but notice little intricacies in her background vocals/layering(that is if you have a good ear for music)
I would say Whitney set the bar ;and yes we all know she influenced Mariah Carey,but I would say Mimi came in and took off where Whitney left. Mariah took powerhouse singing to a whole other level of creativity.
Whitney at her peak is one of the greatest and most iconic of all time