I can't see the difference between the two parents, it happens a lot with the other pictures of this artist too. Which is the difference?
There's no difference but the source.. PIXIV usually have a better quality than twitter, so when it's posted there it can be posted here for it will be the "main" version. It would be good if uploaders would restrain themselves to post a twitter picture here too soon.. Mainly from artists that are known to post their works at pixiv. Also, I think that the lowest quality picture should be flagged for deletion whenever a better one is posted.