Overview
Both come from あまり (“excess, too much”), and both link an extreme degree to a consequence, but they attach differently and take different partners. あまり in this construction — usually …のあまり — marks an excess of emotion or state that causes a result: “so much X that Y happened.” It pairs with nouns and verbs of feeling. あまりにも is an intensifier meaning “too / excessively,” and it pairs with adjectives to say something is so extreme that a consequence follows. The shorthand for students: のあまり with a noun/verb of emotion (“out of sheer X”), あまりにも with an adjective (“far too X”). The two overlap in feel but split by what word class they attach to, which is the key teaching point. The entries lead with a simple example, then a funny one.
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