The customs and excise taxes are often confused. The main difference between customs and excise taxes, is the location of origin for the item being taxed. Customs taxes apply to items that enter the country from another country. Wheres, excise taxes are applied to items manufactured and sold in this country.
Customs taxes are often applied to items purchased in another country and then brought over the border. In fact, customs will ask those crossing the border to declare any items they purchased in another country, so that they can be taxed on the value of those items.
However, customs may allow a certain value of items without paying the tax. In fact, many locations have duty free shops at airports and border crossings where individuals may purchase items without paying the tax. However, they must pay the tax if those items exceed a certain threshold of value.
Conversely, the excise tax is applied to items purchased in this country. The excise tax is often applied to items such as alcohol and tobacco, on a per volume basis. This differs from the customs tax, which may be applied in a myriad of ways, including the weight of the item, the value of the item and the materials which make up the item.
Excise taxes are an indirect tax which is paid to the retailer at the point of purchase. That tax is added to the price of an item on a per volume basis and then forwarded to the appropriate tax jurisdiction.