～から vs ～ので

Both 「～から」 and 「～ので」are used to explain a reason or cause. These days, the difference between the two is getting smaller but they are not quite interchangeable.

Suppose your bus got delayed and you were late for work, which of the following two would you say?

A: バスが遅（おく）れたから、遅刻（ちこく）しました。

B: バスが遅（おく）れたので、遅刻（ちこく）しました。

The more preferred option is B.

A: 「から」 is a word to describe a “subjective reason”. In the speaker’s mind it is the reason for the subsequent event, but other people may not see the connection. Using 「から」 gives an impression that you are blaming the train being late and your boss might say, “why didn’t you catch an earlier train?”

On the other hand, B: 「ので」 is a word to describe a “objective cause.” Using 「ので」 here gives an impression that you could not avoid the situation.

If you see a child doing something dangerous and you want to stop him/her doing it, which of the following do you think is more effective?

C: あぶないから、やめなさい。

D: あぶないので、やめなさい。

In this case, the more preferred option is C because using 「から」 here gives a bit more urgent impression.

If my student studies Japanese everyday because she loves it, I’d prefer to hear:

日本語にほんごが好すきだから毎日まいにち勉強べんきょうします。

rather than

日本語にほんごが好すきなので毎日まいにち勉強べんきょうします。

As the former one sounds much more passionate than the latter one. The latter one sounds quite lukewarm.

Now as seen above, if から or ので is used with a noun or a なadjective, the connections are NOT the same. Please read this post for that explanation.