ar·iff (trf)
n.
1.
a. A list or system of duties imposed by a government on imported or exported goods.
b. A duty or duties so imposed.
2. A schedule of prices or fees.
http://www.thefreedictionary.com/tariff

cus·tom (kstm)
n.
1. A practice followed by people of a particular group or region.
2. A habitual practice of a person: my custom of reading a little before sleep. See Synonyms at habit.
3. Law A common tradition or usage so long established that it has the force or validity of law.
4.
a. Habitual patronage, as of a store.
b. Habitual customers; patrons.
5. customs
a. Duties or taxes imposed on imported and, less commonly, exported goods.
b. (used with a sing. verb) The governmental agency authorized to collect these duties.
c. (used with a sing. verb) The procedure for inspecting goods and baggage entering a country.
http://www.thefreedictionary.com/customs

As spune doar 'Customs And Tariff Bureau', pentru ca, in conformitate cu definitiile termenilor englezesti, 'customs' are si sensul de 'tehnica/procedura vamala' (sensul 5), iar primul sens al lui 'tariff' este de 'taxa/tarif vamal' fara a avea nevoie de nici un determinativ.

In plus, gasiti multe referinte pe net: http://www.google.com/search?hl=en&q=customs and tariffs bu...

Sper sa va ajute.

Succes!