Fionn and Áillen

[Áillen] would burn Tara [the seat of the High King of Ireland] to the ground every year at Samhain [Oct 31/Nov 1] with his fiery breath after lulling all the inhabitants to sleep with his music. This only ended with the arrival of Fionn mac Cumhaill, who inhaled the poison from his spear to keep himself awake and slew Áillen.
~The Boyhood Deeds of Fionn

Now that's a hero, right? Inhaled his own poison to stay awake! For Art Thursday, Fionn mac Cumhaill fighting "The Burner" Áillen. According to Irish History.com:

Fionn Mac Cumhaill, born as Demne, was the son of Cumhaill, the leader of the Fianna, and Muirne, the daughter of the druid Tadg mac Nuadat. Fearing for the child’s safety due to Cumhaill’s death in battle and the enmity of his enemies, Muirne entrusted her son to be raised in secrecy by the druidess Bodhmall and the warrior Liath Luachra.

The name Fionn, meaning “fair” or “bright,” was given to Demne after he killed a dangerous supernatural creature known as Aillen mac Midgna, who had terrorized the people of Tara for years. With his newfound fame, Demne adopted the name Fionn Mac Cumhaill, honoring his father and signifying his bright future as a great hero.

Both of these images seem to be from the same book, but they are quite different. I thought the second one was Áillen because it seemed like there was fire coming out of the creature's mouth but maybe not? What do you think?

Fionn fighting Áillen
illustration by Beatrice Elvery in Violet Russell's Heroes of the Dawn (1914)

illustration to a collection of tales from Irish mythology
Beatrice Elvery, 1914