minibus vs shuttle bus

minibus

noun
  • A small bus, especially one used as transport for small groups. 

  • A sixteen-seater vehicle used as a taxi. 

  • A combined spending bill for multiple departments that is smaller than an omnibus bill. 

  • A small four-wheeled carriage. 

shuttle bus

noun
  • Short-haul, limited-passenger buses, typically privately owned, such as by hotels, retirement villages, etc.; a shuttle. 

How often have the words minibus and shuttle bus occurred in a corpus of books? (source: Google Ngram Viewer )