toutyakukou ni yotte, syukkouzikoku ga tigau.

Here によって means depending on, according to, or based on.

So the idea is:

The departure time is different depending on the arrival port.

In this sentence, によって shows the factor that causes variation.

Yes. によって comes from よる, which in this kind of grammar means to depend on, to be due to, or to be according to.

This is not the everyday 寄る meaning to stop by. It is a different よる, often associated with meanings like:

• depending on
• according to
• by means of
• because of

In modern Japanese, learners usually just memorize 〜によって as a set expression.

Because によって is the grammar pattern that means depending on.

• で would normally mark a place, method, or cause, but it would not naturally give the meaning depending on
• は would make 到着港 the topic, but it still would not express that the departure time varies according to it

So:

• 到着港によって = depending on the arrival port

That is exactly the relationship the sentence wants.

到着港 means arrival port, or more naturally in many contexts, destination port.

It refers to the port where the ship is supposed to arrive.

This is a compound noun:

• 到着 = arrival
• 港 = port

So together, 到着港 is the port of arrival.

Because 出港時刻 is the thing that differs.

• 出港時刻 = departure time
• が marks it as the subject of 違う

So the structure is basically:

• As for the arrival port, depending on that, the departure time differs

Using が here is very natural because it identifies what is different.

If you used は instead, it would sound more contrastive or topical:

• 出港時刻は違う

That can work in some contexts, but が is more neutral here.

No. Here 違う means to be different or to differ.

Many learners first meet 違う in conversations like:

• 違う！ = No, that's wrong!

But its basic meaning is simply to differ.

So in this sentence, 出港時刻が違う does not mean the departure time is incorrect. It means the departure time varies or is different.

Both can be possible in some situations, but the nuance is slightly different.

• 違う focuses on difference
• 変わる focuses on change

So:

• 出港時刻が違う = the departure times are different
• 出港時刻が変わる = the departure time changes

In your sentence, the point is that different arrival ports have different departure times, so 違う is a very natural choice.

Because these are standard compound nouns.

• 到着港 = arrival port
• 出港時刻 = departure time

Japanese often combines Sino-Japanese nouns directly like this, especially in formal, technical, or written contexts.

You could sometimes express similar ideas with の, but it would usually sound less compact and less natural here. For example:

• 出港の時刻 is possible, but 出港時刻 is more concise and more typical in formal wording

So the compounds are normal and natural.

A very literal breakdown is:

• 到着港 = arrival port
• に よって = depending on
• 出港時刻 = departure time
• が = subject marker
• 違う = differs / is different

So, literally:

Depending on the arrival port, the departure time differs.

That is already quite close to natural English.

The comma is helpful, but not absolutely necessary.

• 到着港によって、出港時刻が違う。
• 到着港によって出港時刻が違う。

Both are fine. The comma just makes the pause clearer after the depending on phrase.

As for the spaces: no, normal Japanese usually does not use spaces between words like this. The spaced version is mainly for learners.

Standard writing would be:

到着港によって、出港時刻が違う。