Are "と" and "から" equal when they mean "from"?

Question

When "と" and "から" can both be translated as the English preposition "from", do they have the exact same meaning/nuance and are they interchangeable?

For example, in the sentence 「 確【たし】かに中沢{なかざわ}部【ぶ】長【ちょう】と 離【はな】れることは残【ざん】念【ねん】だ。」, can the "と" be replaced with "から"?

Likewise, in this sentence 「やめる前【まえ】に直【ちょく】接【せつ】彼女【かのじょ】から聞【き】きました。」, is "から" replaceable with "と"?

Answer 1

That use of と should be conceptualized as “with”^[1], and not “from”.

“Xと離れる” is “to separate^[2] with X”. Since you can both separate with and separate from something, both と and から work here (albeit with the subtle difference between “separating with” and “separating from” something^[3]).

“Xから聞く” is “to hear from X”. Replacing this with と would change the phrase to mean “to hear with X”, as in “I heard it with her (彼女と聞いた)”. Alternatively, the と can function as a quotative particle, where “Xと聞く” would mean “to hear that X”, as in “I heard that she is a girlfriend (彼女と聞いた)”.

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Footnotes:

1. In the sense of either “accompanied by” (I will go with you) or “in some particular relation to” (She agreed with me), but not “by use of” (Cut with a knife). See also: Confusion with Japanese particle と in its multiple uses.
2. Verb as used without object. (When used with object, the verb is 離す)
3. I understand that in English “separate from” is the standard preposition choice here. I just wanted to illustrate the から/と difference. “To separate from my parents (親から離れる)” connotes a starting point in space/time from which I am the one moving away, while “to separate with my parents (親と離れる)” feels more like a mutual split where I am not necessarily the primary mover. (To complicate things a bit, since と can also mean with as in “accompanied by”, you can say for example グループから親と離れる to mean “to separate from the group with my parents”.)