The cubic yard is a unit of volume derived from the imperial system of units. It uses the symbol yd³.
It equals the volume of a cube with edges that each measure 1 yard. It is equivalent to 27 ft³, 46656 in³ or ≈ 0.764554 m³.
The yard (and derivatives like the cubic yard for example) are the same in both the imperial systems and US customary systems so require less conversion systems to calculate / convert to SI or metric.
The cubic metre (or cubic meter; US spelling) is a unit of volume and is derived from an SI unit with the symbol m³.
1 cubic metre is exactly 1000 litres. It is also ≈ 6.29 barrels, ≈ 220 imperial gallons and ≈ 35.3 cubic feet.
1 cubic metre of water in normal conditions (≈4 °C) weighs exactly 1000 kg (or 1 tonne).)
The cubic metre is the unit used to measure water usage and often water bills are broken down into how many m³ has passed through the property / business.