Green: $2.40/hour, 2 hours limit
Orange: $1.70/hour, 3 hours limit
Sky: $1.20/hour, $7.00 maximum
Pink: free, 15 mins limit
Yellow: motorcycles
Blue: disabled
Source: http://www.darwin.nt.gov.au/sites/default/files/DCCParking_Brochure_June25_v2.pdf