まるで～ようだ・
ようだ alone can be a guess ("it seems") or a likeness ("like"). まるで in front settles it from the first word: "just like". かのようだ is "as if", usually for what is plainly not so.
as if
Although he had checked nothing, he spoke as if he knew everything.
Just like
まるで + … ようだ／みたいだ
ようだ and みたいだ join on as they always do: まるで夢のようだ, まるで子どもみたいだ.
As if
Plain form + かのようだ
No の or な before か. A noun or a な-adjective usually takes である: 主人であるかのように. Before a noun it is かのような, before a verb かのように.
まるで: a likeness, not a guess
ようだ and みたいだ can be your reading of the signs. With まるで in front, that reading is gone: you are saying what something is like, and you know it isn't really so.
He seems to be Japanese.
Your reading of the signs. He may well be.
He is just like a Japanese person.
A likeness. He isn't, but you would think so.
In the morning sun, the sea shone like a sheet of golden cloth.
There was a stillness in the town, as if time had stopped.
This room is just like being in the middle of a forest.
In conversation, みたいだ.
まるで分からない is a different まるで: with a negative and no ようだ, it means "not at all".
かのようだ: as if
か takes the guess out of ようだ: what comes before it only looks that way. まるで often goes with it.
He seemed to know nothing.
Your reading of the signs. He may really not have known.
It was as if he knew nothing.
He knew. It only looked that way.
The hall fell so silent that it was as if even time had stopped.
They had only won the first round, but the players celebrated as if they had won the whole tournament.
She came back looking as though nothing had happened.
The issue was actually complicated, but he explained it as if the answer were obvious.
明らか is a な-adjective, so である.
You meet かのようだ in novels, essays and news features far more than in conversation.
Close neighbours
The base. With no まるで and no か, it can be a guess from signs, and the guess may be right.
The lights are off. It seems no one is there anymore.
ようだ as people say it in conversation. みたいに is the everyday way to say "as if".
He always talks as if he knows everything, doesn't he?
ふりをするN3
Pretending on purpose. かのように only says how it looks; ふりをする says the person means to be taken that way.
Although he knew the answer, he pretended not to know.
Check yourself
1Had she heard?
彼女は
Choose an answer to see why.
2The ground is wet this morning. You didn't see any rain, but you think it must have rained in the night. Which do you say?
Choose an answer to see why.
3Which one fits?
彼は
Choose an answer to see why.
More detail
In stories かのように is also for what a narrator can't know: 彼女は何かを思い出したかのように立ち止まった, "she stopped as if she had remembered something". Perhaps she had.
English shifts the verb after "as if": "as if he knew". Japanese doesn't. 知っているかのように has the same 知っている as a plain statement would.
More sentences
The wind sounded as if someone were crying.
As I listened to him, I felt as if I had been there myself.
She slowly opened her eyes, as if waking from a long dream.
Spring has only just begun, but today it is as hot as if summer were already here.
His leg was injured, but he kept walking as if he felt no pain at all.
He was only a guest, but he behaved as if he were the master of the house.