Different dimension?

When I started this blog I intended to do series of examples in principles of animation.
These examples are aimed to improving my skills and developing new that I don't have.

I wanted to do it old school: 2D animation and 3D as an upgrade of skills.
I from start in my animation, used 3D, and never tried doing 2D animation, since I found scanning lot of drawings tedious.

But, with tablet in hand, I dared explore animation from its foundations up. At the very start I'm at a theoretical question:

What is the difference in process between 2D and 3D animation?

Yesterday I watched Jason Ryan's video and seen 2D process.

Cells are drawn in, on one's, two's or with any timing you see fit. Spacing of objects gives the speed to animation, as well as spacing between in-betweens :)

Ease-in/out is done by placing in-betweens, without changing the exposure time of each cell. If need be, you can adjust exposure later.

So, can this be copied to 3D as is?

In 3D, Ease-in/out is done by changing property of objects' curves (keys). Computer does in-betweens.

So only timing decision is where to put the keys and what frame rate it will be. There is no question, will animation be on one's, two's or three's.. Or is there?

Well I think its interesting question, I will try and find the answer to. As always any help is appreciated.