Luna is noticeably shorter than her sister and clearly is not as regal as her. But why? Celestia wouldn't be too much older than Luna so shouldn't Luna have caught up?

6221706
Because..... Luna's the Younger Sister.

But she should have caught up. Say if you had a sister 2 years younger than you, then she wouldn't always be shorter than you. You'd both be the same size at some point in your lives, especially if you were immortal, like Celestia and Luna.

6221981
okay.......

What, you think I over-analyzed? (I probably did)

6222214
I guess =3