Is there canonical reconciliation of the two? Yes, there are actually multiple attempts to reconcile this issue, all coming from different cWoD sourcebooks.
Is there a reconciliation of reconciliations? No and for good reasons.
So is there a reconciliation I should use? Yes, the one in the book you're currently using.
That was the short answer, for the long, bear with me for a minute.
cWoD games despite often being described as happening in a single universe are explicitly separate and irreconciliable. Werewolves from Vampire: the Masquerade are not Garou from Werewolf: the Apocalypse. Umbral demons from Werewolf are not the same entities as the ones in Demon. Mage's Shadowlands are not Wraith's Shadowlands. This is an intentional design paradigm that stems from the fact that each game explores completely different topics and has immensely disparate character power levels. It's "safer" (more convenient) to say these are separate games, both in terms of mechanics and lore, otherwise identity of God is the least of your worries.
cWoD is also ripe with self contradictions. Some of them were so bad they got turned into in-jokes (Rasputin, anyone?). Even books from the same line contradict themselves. Sometimes even the same book has contradictory claims (I'm looking at you, Mage: the Ascension). Some say it's sloppy design, others that it's a conscious choice to present differing world-views and highlight the obscurity of The Truth1. Others yet say that's what happens if the studio smokes too much. Arguments aside, the reality is that the lore is generally muddy and unclear and seeking for The Truth is a futile endeavour.
Finally, cWoD's entire philosophy rests on a fact that reality is just a reflection of one's perception, beliefs and whimsy. It is entirely possible that what is true to a Demon is heresy to a Werewolf and uninformed fantasies for a Mage. For example, Mage asserts that there were Pure Ones - creators, whose remnants are now other celestial entities. It also accepts the Triat (Wyrm, Wyld, Weaver) as personification of three governing powers of the Tellurian (Primordial, Dynamic, Pattern). It ALSO accepts that on some level each entity that has human belief behind it exists and has powers approaching it's imagined human ideal, so God-Creator believed to be the creator would also be the creator. It makes no effort to reconcile the two. It is the same with Demon. What is demonstrably true and works and by both theory and experiment has been proven to be accurate for a Demon can also be demonstrably false and disproven and not working for a Werewolf2.
My suggestion, therefore is:
- Don't think about it too hard.
- Pick one and roll with it.
- Then pick the other and roll with it for a while too.
- Make sure everyone understands that there is no one proper answer.
- Have fun.
1 - That if one assumes some, if not most, of the books fluff is written In-Universe.
2 - If Gaia is a celestine or something even bigger is not fully clear because of contradictions. The hierarchy presented at times tells Gaia > Triat > Celestines etc, other entries list Gaia as a Celestine (Umbra Revised p 103f) or a genealogy (as in Hengeyokai, p 130ff). However, 1 applies.