The city council may establish one or more separate benefit zones within the district based upon the degree of benefit derived from the improvements or activities to be provided within the benefit zone and may impose different assessments within each benefit zone. If the assessment is to be levied on businesses, the city council may also define categories of businesses based upon the degree of benefit that each will derive from the improvements or activities to be provided within the district and may impose different assessments or rates of assessment on each category of business, or on each category of business within each zone.