What is the difference between "trash" and "junk"? [closed]

In my e-mail account there are two sections with the labels "trash" and "junk" and I would like to know the difference between these two words.

I only can say that "junk" might be something that was once useful. But what is the real difference?

I will appreciate it if someone edits my question's tag because I do not know which one is the best.

Junk in the modern context of junk mail refers to unsolicited messages (advertisements and possibly scams) which you probably don't want to open. Trash (in the context of email) is messages that were useful, but that you have deleted because you no longer need to keep them.

In the context of email, junk refers to junk mail otherwise known as spam (random ads, possible scams, or anything else your email program may file as spam). Trash is when you delete an email. They can be connected because for many email programs, junk mail that sits in the spam/junk folder for more than 30 days will be deleted to trash.