The metric and imperial systems are very different from one another. The metric system is the one used by most countries, but the imperial system is the system which was used by the British Empire. It is still used in the USA.
In the metric system, one kilometre is one thousand metres and one kilogram is one thousand grams. However, in the imperial system, one mile is 5280 feet and one pound is sixteen ounces.
The metric system also has metres and centimetres. One meter consists of one hundred centimetres. In the imperial system, one yard consists of three feet and one foot consists of twelve inches. The metric system is based on the decimal system. The imperial system is not.
The metric system is undoubtedly easier to use than the imperial system. However, those who are familiar with the imperial system often find it difficult to switch to metric. In Canada, the metric system is official, but many people still use imperial weights and measures in their daily lives.