Both are the very strong beings on their own, Junko the divine spirit and Morgan the High-class type Fae (the King/Queen Fairy)
Both are the sworn enemies of a kingdom with the exact opposite way, Junko is the sworn enemies of Lunarian Capitals as her invading the moon, Morgan is the sworn enemies of Avalon Le Fae Kingdom due of her absolute tyranny that has run over 2000 years
Both has perfected their abilities, Junko purify her own grudge to the point where the strengthening of it has made her an embodinment of her resentment as a divine spirit, she also can use this to bring anything back to their godly nature, Morgan has mastered the magecraft more than anything that the Fae has done in Lostbelt 6 where in the point she made the Spear of the End: Rhongomyniad, an high rank Noble Phantasm that acted as the anchor of Far Side of The World, into a mere powerful Magecraft
But most importantly, they have a similar thing: their madness and grief
Junko has went mad and became things of Pure Fury due of her loss to her son, because of Hou Yi and Chang'e, mourning and grieving transformed into a grudge, and it transformed into a fury from the purify, and with that power she sworn to kill Chang'e, start by murdered Hou Yi and later on targetted the Moon and Lunarians even if they are not responsible for it, hence the invasion of Moon
Morgan has went mad (hence Berserker Class) because
originally, she's a paradise fairy sended by the Earth, Tonelico, to stop the calamities and disaster that struck over Lostbelt 6, however all of her effort means nothing from time to time, from loop to loop, from that first time she was betrayed by her own race in Londonium Fall, and for millennia, she has been answering Britain’s time of need whenever Calamity threatens it, but she’s been increasingly ostracized. Whenever there isn’t a threat requiring her, she’s chased out of town and forced to hide in exile. Over and over, she fulfills her duty as Britain’s saviour, the Avalon le Fae, and as soon as it’s done is despised for it. And after her attempts at creating lasting peace are repeatedly torn down by the fairies practically on a whim, culminating in the deaths of the Round Table and Uther, Tonelico can’t take it anymore. She just stops caring about saving people, as it always leads to being betrayed, and inevitably Calamities return to threaten the country again, thus by over 12,000 years old because of time loop, she's gave up to undo the calamities and disaster
So, she turns on the memories she received from the actual Morgan Le Fay (The Cruel Witch of Britain from Proper Britain History) from 6000 years ago about the existence of Lostbelt, Alien Gods, Fantasy Tree, and so on, thus changed her name from Tonelico to Morgan
And by hundred years forward, the Fae Kingdom collapse and Tonelico (now as Morgan) use this advantage when Avalon Le Fae was in vulnearable state, by drained the power and cutting down the Fantasy Tree that substained the whole Lostbelt 6, waged the winter war using it's power, and successfully unify the Fae Kingdom in her cold hand by force, thus history calendar has rewritten and by that, the new fae kingdom has born and ruled over 2000 years
Now, they are not by anymean a pure evil neither, both still has the heart and a friends they adore, Junko has Hecatia her bestie and Clownpiece, and she has an interest with Reisen, Morgan has Habetrot and the Fairy Knights of Round Table, most importantly Baobhan Sith as her daughter