Now, for knowledge, while it is a "limit" of sorts to the Ainur,
I do not consider it a limit on capability so much as a limit on imagination. For example, when Morgoth's song overcomes the music of other Ainur, none are harmed, not even those nearest to him. Furthermore, all the actual capabilities of the Valar appear equal at this stage, as any could have gone the route of Melkor if they had decided to repute Eru's lessons and strike out on their own.
- "Of this we may be sure, we children of small strength: any one of the Valar might have taken the paths of Melkor and become like him: one was enough." - The Nature of Middle-Earth, Part Two: Body, Mind and Spirit, VII: Mind-Pictures
It stands that the Ainur do not so much differ in literal power so much as knowledge at this stage, with said knowledge being the grounds upon which they are compared.
Of course, this lack of knowledge isn't restricting beyond say their creativity, they can go beyond their given roles due to their free-wills afterall. Therefore, there isn't a restriction on their ability to influence/create all possible words (having the capacity even if not the knowledge seems acceptable judging by profiles like
The Star-Maker).
- "...Melkor knew his will without questioning it; and he knew that Manwë was bound by the commands and injunctions of Eru, and would do this or abstain from that in accordance with them, always, even knowing that Melkor would break them as it suited his purpose." - The Nature of Middle-Earth: Part Two, IX ÓSANWE-KENTA
- "In this Myth the rebellion of created free-will precedes creation of the World (Eä); and Eä has in it, subcreatively introduced, evil, rebellions, discordant elements of its own nature already when the Let it Be was spoken." - Letter 212
Moreover,
there isn't a true "power" difference in the "punch harder" way. For example, even at point-blank (relatively speaking on such a higher scale), none of the "lesser" Ainur were harmed by Melkor.
- "But the discord of Melkor rose in uproar and contended with it, and again there was a war of sound more violent than before, until many of the Ainur were dismayed and sang no longer, and Melkor had the mastery..." - The Silmarillion: AINULINDALË
By this I was somewhat trying to differentiate the idea of literal power from knowledge.
Ainur at this stage of their existence do not have a outright definition to their "might" beyond knowledge, yes. Indeed, this is why Manwë is mightier than say some Maiar.
"
Knowledge of the Story as it was when composed, before realization, gave them their measure of fore-knowledge; the amount varied very much, from the fairly complete knowledge of the mind of the Creator in this matter possessed by Manwë, the 'Elder King', to that of lesser spirits who might have been interested only in some subsidiary matter (such as trees or birds)." - Letter 200. - emphasis on fairly, Manwë comes as close as possible, no more than that.
But
this doesn't seem to be literal power in the sense of "Goku's Kamehameha beats Vegeta's Galick Gun".
Ainur at this stage cannot harm one another and can only overcome one another via "knowledge". Melkor overcame lesser Ainur with his discordant music, but no harm was done upon those who were against him despite the great power of the Musics.
Moreover, while knowledge limits what they can "create", it is only because they obey Eru's laws. When Melkor decided to become disobedient, he made something he was not taught, the discourse of Evil. This is in contrast to Manwë who naturally would never go beyond them.
"...Melkor knew his will without questioning it; and he knew that Manwë was bound by the commands and injunctions of Eru, and would do this or abstain from that in accordance with them, always, even knowing that Melkor would break them as it suited his purpose." - The Nature of Middle-Earth: Part Two, IX ÓSANWE-KENTA
Therefore in this sense, knowledge can be used to say X Ainu is "mightier" as they possess more ability to create, but only because they obey Eru. Once Eru is disobeyed, Ainur can go beyond their knowledge and make whatever they imagine, just like a writer. It is essentially the limits of what they can imagine not output.
It's essentially that the Ainur are assistants to the author until one goes off on their own to become their own author... well not really as Eru cannot be equaled, but there you go.
Something I acknowledge is that this answer to the issue of knowledge isn't entirely water-tight as it is ultimately a interpretation (albeit all things are, but this in particular).
It is a rather singular issue for High 1-A+ that I believe has been mostly dealt with, but due to the interpretability of this final potential issue, I'm more accepting of a possibly rating for the Ainur rather than a solid one.