I don't know of any lore that backs up my take on this, but the u makes them bigger or the o means they are smaller
One more thing to note is that this is a rare planeswalker instead of a mythic one
However, if youre planning to buy some of the boosters, what cards should you be looking out for, or conversely, which cards might have their single value hit most thanks to the reprints
Braids, Arisen Nightmare is one of the purest forms of Mono Black Aristocrats you'll come across: like Baba Lysaga, Night Witch, Braids is a powerhouse card draw engine that drains opponents, but unlike Baba we aren't jumping through hoops to get our value, we're just playing a classic Aristocrats list that happens to gain crazy value from our commander but isn't built entirely around her
Those are far more important than just looking down a checklist and making sure your deck doesn't violate any of the rules