Difference between 'speed mail' and 'express mail'

[Guest]

Test No. incompl/inter-16 "Letter Writing", question 4

If you want this letter to reach the bank tomorrow, you have no choice but to send it by ......... mail.

(a) speed
(b) express
(c) excess
(d) fast

Test No. incompl/inter-16 "Letter Writing", answer 4

If you want this letter to reach the bank tomorrow, you have no choice but to send it by express mail.

Correct answer: (b) express

Your answer was: incorrect
If you want this letter to reach the bank tomorrow, you have no choice but to send it by speed mail.
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Please tell me the difference between speed and express mail

[Alan]

I don't know any use of speed in connection with mail/post. Express would be used for the post, trains and any service like dry cleaning where you would pay extra for an extra fast service.
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English as a Second Language
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