The bushel is a unit of volume in the imperial unit system with the symbol bsh.
1 bushel is equal to 8 dry gallons, or 36.36872 litres.
The bushel was introduced in England as a unit to bridge the relatively large gap between a pound and a ton - and was used largely to measure volumes of liquid being imported and exported following the Norman Conquest such as wine and ale.
The name bushel comes from the ancient French 'boissiel' which means 'little box'.
The barrel is a unit of volume used in the oil industry with the symbol bbl.
Oil is more commonly expressed in terms of cubic metres (m³) but in the US and in the economic world (mainly because such a large percentage of the world's oil is shipped to the US) as barrels.
The measurement of the barrel originated in the US at the first oil well in Pennsylvania. There were so many variants of barrel size (including those used for wine and other goods) that the distrust became so prevalent a central and standard barrel size was created. This was finally established in 1872 as 42 US gallons.