Royal Dutch Shell is Oil and Gas Company headquartered in Netherland and Regitered Office in UK. Royal Dutch Shell A and Royal Dutch Shell B are not two different companies. Key difference is Royal Dutch A and B shares is related to Taxation and Dividend.
Caterpillar with 2017 sales and revenues of $45.462 billion, Caterpillar is the world’s leading manufacturer of construction and mining equipment, diesel and natural gas engines, industrial gas turbines and diesel-electric locomotives. The company principally operates through its three primary segments - Construction Industries, Resource Industries and Energy & Transportation - and also provides financing and related services through its Financial Products segment.