Bourgeois is more of a social class distinction than economic. In the middle ages, there was the gentry and the peasants. Gentry owned all the land and hired artisans make their clothes and furniture by hand. Peasants worked the land and made their own clothes and household items. With the industrial revolution, there arose industrialists who owed factories to produce the new range of mass produced items such as clothing, furniture, wagons, etc. They were the new bourgeoise who lived in cities and hired peasants to work in their mills and factories. Some amassed great wealth but they were looked down upon by the gentry because they did not have hereditary names or money. Earning money was considered dirty compared to inheriting it. So the bourgeoise may have been wealthy and lived like royalty but they had a lower social status than the gentry and higher than the peasants and factory workers. It's a matter of semantics whether you call that "middle class" or "merchant class" or "bourgeoise".