I think you have to naturally have a nice tone to your voice. Have no idea how people pick up vibrato and other fancy stuff like that D:

Of course!

Singing is two things:
1. Vocal placements.
2. Ear training.

It's all about finding a pleasant tone in your voice and tuning your ear.

My voice is not too shabby,but I've managed to learn how to properly place my voice.

People are always intimidated when they hear their singing tone is not pleasant because they don't yet know how to properly find their placement.

I know where my placement is and I know where every singer's vocal placements are as well from Mariah to Christina.

Tiziano and Buble has the same placements, they sing alike, but they're both distinctive from another because they shape their resonance differently.

What's physically different though? Like if two people both did those two things well and one had like a bigger range and more power, what's different inside of them physically?

There's a lot of factors:
1. Vocal health, etc.
2. Genetics
3. For range like Mariah's, you need to focus more on the balance between the air pressure and the vibrations of your chords. The higher you go, the faster your vocal chords vibrate, and your chords zip up all the way up just enough to allow vibrations.
4. For power like Whitney's, more focus is on lowering the larynx to allow more resonance.

I'm typing this through mobile so I may not make sense sorry. I'll edit this tomorrow when I use laptop.

And singing from the diaphragm is the biggest pile of **** you will hear from a vocal coach.

Bad vocal coaches will teach you to sing from the diaphragm and will force you to do breathing exercise...

If your vocal teacher teaches either or both of those two things, then you better drop them, you'll just be wasting your money and effort.

A good vocal coach will teach you proper placement. Vocal placement is the key to singing great.

With proper placements, good breathing will come secondarily and naturally, support will come.

You don't breathe to sing. You don't support to sing. You don't use your diaphragm to sing.. That just never make sense.

What makes sense is properly placing your voice to sing.