I got both examples from here and here respectively. I understand what these sentences mean, but I'm a little confused as to how sentence particle ’に’ works in these sentences. If both of the 自動詞 and 受身形 make use of particle に, does that mean 自動詞 and 受身形 are exactly the same? If so how could we differentiate the use of 自動詞 or 受身形, or to be clear, why would there be two different forms? Shouldn't there at least be like a difference in nuance?
Is there a difference in nuance for both these sentences? Is it that one is more commonly used than the other? Any difference in meaning for both of them?
Also, how would you understand the use of 'に' here? If we were to translate them literally, do they both mean "by" in English? Or is there something else I don't know about?
Sorry if it sounds like a dumb question, but this has been troubling me for a long time.