将来 and 未来: future prospects and the future
Compare future prospects and plans with the future as a time or world.
Future plans and prospects
将来 is read しょうらい and is often used for future life plans or prospects. 「将来、教師になりたいです」 expresses a wish to become a teacher in the future.
「この会社には将来性があります」 evaluates the company as having potential. It does not establish that future success is guaranteed.
The future as a time and world
未来 is read みらい and refers to time beyond the present or a future world. 「未来の都市を描きました」 means that the speaker drew a city of the future.
「未来はまだ分かりません」 says that the future is not yet known. The word does not necessarily refer only to a very distant era; its scope depends on context.
Different views of an overlapping future
Both 「子どもたちの将来」 and 「子どもたちの未来」 can refer to children's future. The first can suggest life prospects or paths, and the second the time and possibilities ahead.
The words are not divided into individuals for 将来 and society for 未来. A company can have prospects and a person can have a future; focus on prospects versus the future time or world, not the size of the subject.
Does 「将来の夢」 refer to something already achieved?
Show the answer and why
No. It refers to a dream for the future. 「将来の夢は教師になることです」 describes an aspiration to become a teacher, not the speaker's established current job.