"Dream of" and "dream about". Is there a difference?

Are "dream of" and "dream about" interchangeable or is there a difference between them in meaning and usage.

Answer

To dream of something implies a want, a need, a desire:

I dream of traveling the world

I dream of world peace

I dream of Jeannie

To dream about something is to literally dream about something, and it's usually presented in the past tense:

I dreamt about winning the lottery

I dreamt about flying

I dreamt about being a millionaire

To use it in the present tense is more passive.

I dream about becoming rich

I dream about Jeannie

I dream about wonderful things.

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To dream of uses a different past tense form as well.

DREAMED

I dreamed of having the perfect house

I dreamed of winning the lottery

I dreamed of paradise on the beach.

These have nothing to do with dreaming while asleep. They are all imagined, hoped for, dreamed of...