AB vs. Sweetie Belle: Personality differences?

So I was thinking about what the personalities of the CMCs are, and I found myself kinda drawing blanks* on exactly what are the differences between AB and Sweetie Belle’s personalities.
 
Scootaloo is obvious, with her being a tomboy who’s the most likely to just rush into things without thinking it through. But with the latter two, I’m not quite certain. Maybe it’s because it’s been a while since I’ve last seen an episode with them, but in any case, I would appreciate some assistance on this. The best I can think of is that SB is a bit more meek and careful than the others, but even that I think is very downplayed.
 
_{*No pun intended.}

@Background Pony #FA55
 
They are a little bit interchangeable. I tend to see Sweetie as the most driven and mature of the CMC. Which is funny as she started as the airhead.

@gingerninja666  
I don’t think it was so much airhead, as Sweetie Belle was the least intelligent of the three. When it came to doing the right thing, she was usually the most on the ball.
 
She’s also the most vindictive. Apple Bloom got mad at Applejack sometimes, but generally just set out to prove she could do whatever it was Applejack said no to. Sweetie Belle basically disowned her own sister. Twice.

If you know Apple Bloom and Sweetie Belle, their personalities are very different.

@DarkyBoode32  
In seasons 1-3 as well?

@Background Pony #BF34  
In every season

@DarkyBoode32  
Any examples off the top of your head?

@Background Pony #BF34  
Their relationships between their sisters, Rarity and Sweetie Belle barely spend time together, Apple Bloom and Applejack do, in the episode Sisterhooves Social for instance. Sweetie Belle isn’t good at painting props, Apple Bloom is, in the episode The Show Stoppers. Sweetie Belle is more sensitive than Apple Bloom, whenever something bad happens she bursts into tears, in the episode One Bad Apple. Sweetie Belle exclaims more than Apple Bloom does. Sweetie Belle also appears to be more amusing and attractive than Apple Bloom is. Apple Bloom probably is less cautious, in the episode The Cutie Pox for instance. Those were examples taken from the first 3 seasons.

One the earth pony and the other unicorn