@Bonberjean
That’s how Derpibooru works, it doesn’t care about the age of the comment

@Liggliluff
Hmmmm…. not sure if you’re serious or trying to make a joke, I’ll assume is the former.
I received a random notification on this image at date of my previous comment, the most recent comment before that was years ago, so it makes no sense to get a notification out of the blue of something that was not updated for at least 4 years…

@Bonberjean
Because you made a comment 5 years ago

Why did I just got a notification on this image?

@Background Pony #73C0  
I do my research

@Liggliluff  

Their breasts are in different sizes. But I don’t think it’s intentional, but rather the artist drawing the clothes drawing the boobs freely. We need to see them wearing other clothes and from the side so we can see if their boob sizes changes.
 
I have tried tracing different poses and to my knowledge, all their body parts changes sizes slightly depending on what pose they do, including boob size.
 
I tried overlaying it, to see if their boobs were the same size. But there are some differences.  
 
Pinkie Pie and Rainbow Dash has the same size, as if they were made out of the same base.  
Rarity’s dress follows the same shape as Pinkie Pie, but the neck is further back.  
Applejack’s boobs don’t go out as far, but the neck is also further back.
 
We would need more data before being able to make a definite claim.
 
But I still wouldn’t be surprised if their boobs are meant to be the same, just like how the ponies all are based on the same model.

@HorsesandMuchMOAR  
She did. As did Twilight.

@Background Pony #194A
 
Wow, Sunset must be really envious that she did not have some magical face mark, so she tried rubbing her own face.

@MetaKnight145
 
But here Rainbow is the cutest, other than Pinkie.
 

@neo4812  
First off: gross on you.  
Second: It’s their shirts that’s different; Rarity is wearing a tighter one.

you can see there diffident breast size, rarity looks to be the largest of the group

flatjack < pinkie pancake < rainbow distractions < flutter-not-so-shy < rarity’s rarities  
rip Applejack.

They look so cute when they smile like that.

I suppose this matches the old dolls a bit (which I find a bit odd) but at the same time they only had the marks during the power up sequence and they didn’t have them in the super form.

@darknessRising24  
Well, Fluttershy’s bust hidden by her hair, so whether she or Dash is the biggest is still up for grabs (pun fully intended). So much for Pegasi being the slender, athletic ones, though.

@Alexlayer  
And RD is the biggest? Well that’s a fandom joke shot down….

@Glimmering Spectacle  
Huh, so AJ’s actually the smallest.

I gagged when this happened. Possibly not literally.

@Legioner8  
 
One cheek’s as good as another.

@SaburoDaimando  
Dang, you beat me to it!

@Legioner8  
you can put, you just can’t show it