With apologies to those whose profession is to teach the English language and to those who believed they had finished learning about the English language, I spend a few words on the notions of "simile" and "metaphor."
I know the difference between the two. In fact, I know it so well that I looked up both words four or five times while preparing for this topic, and then asked my daughter Julia just to be sure. A simile is a comparison using the word "like" or "as." (The Beltway is like a concrete lasso.) A metaphor is an equivalency. (The Capitol dome is the crown of democracy.) In a simile, things are similar, but not exact. In a metaphor, things are equivalent.
I also violate my self-imposed rule of speak of only one word of prayer at a time. "Mi kamokha...umi domeh lakh" seemed to me to be part of a pair. I wanted them to be simile and metaphor, but they did not cooperate. The line between the two in Hebrew seems to be a little blurry, illustrated by the translation I found for "metaphor" in Hebrew, which was "metaphora." Other than that, simile and metaphor carry the same Hebrew meanings.
But there is no denying that "kamokha" (meaning "like you") and "domeh lakh" (meaning "comparable to you") are not must parallel terms, but meant to convey two distinct ideas about God. Having just recited a list of God's powers over nature and even death, the words of prayer in our mouths ask an almost obvious question: who or what is the reference point for this set of abilities? Domeh is also found in the word "dimayon," meaning imagination. What could we possibly imagine that is like God? The answer, of course, is no one, nothing.
Except, of course, those beings created in God's image/imagination. We were created to be like God and to realize the part of God that makes us uniquely Godly among all of creation.