Your best bet is to read about 'carry' and 'transport' at http://www.thefreedictionary.com/carry Skip the long lists of definitions. There are two 'usage notes' that you can read. The first one says: "Synonyms: carry, bear1, convey, transport These verbs mean to move while holding or supporting something. 'Carry' is the most general: The hikers were carrying backpacks and sleeping bags. The train carries baggage, mail, and passengers. 'Bear' can denote the movement of heavy loads: The river barges bore grain and coal downriver. It can also suggest formality or ceremony: The sergeant at arms entered the chamber bearing the mace. 'Convey' often implies continuous movement or flow: A moving belt conveyed the parts along the assembly line. 'Transport' emphasizes movement of goods or people from one place to another: Refrigerated trucks were used to transport the milk from farm to market. Buses stood by to transport the evacuees to area shelters." As for a horse, yes a horse can 'carry' people. But we would probably use 'transport' for a horse, if it is used to 'move goods from place to another' on a regular basis. This is similar to a 'truck'. Also, way down at the bottom of the page, you can set the page for Spanish translations, and it will give you *many* examples.