These are used to transport good between industries, stores and storage. To select which you might want to use for your complex you have to find out first how much and at which distance you will transport your goods. As Trucks get mostly used for small - normal (8-20/ week) amounts of resources and for ranges up to 75 fields. Trains are able to transport between (10-40/week) or more at a range up to 150 fields. Ships mostly provide a good transport if you have enough water as they got real large cargo space to make up for the limited speed. Planes should be used for transporting expensive wares as they can transport up to 12/week even with a transport way of over 200 fields.
Ground vehicles will get a hill penalty while driving on one. (30% less speed)