The terms people usually use to describe the spectral differences are "vocal weight" and "resonance". Trans people and voice actors probably have the best resources on voice and how to talk about it, like @zheanna.bsky.social has some great videos on this www.youtube.com/watch?v=gZWQ...
youtube.com
The Big Picture of Voice Feminization | A Comprehensive Overview | Lecture & Demonstration
YouTube video by TransVoiceLessons