潮流 and 海流: a ship's course, social change and a model
Read 潮流 and 海流 through a ship pushed by a current, social change, map arrows and a model survey ship. Keep water meanings, metaphor and represented objects distinct.
潮流 moving a ship and describing social change
潮流 (ちょうりゅう) means current or trend. 「船は強い潮流に押されて進路を変えた。」 means “The ship was pushed by a strong current and changed course.” The water current pushed the ship, and the ship changed course.
「技術の進歩が社会の潮流を大きく変えた。」 means “Technological progress greatly changed the course of society.” The object changed is the course of society. The sentence uses a social-flow metaphor rather than reporting society moving physically through water.
海流 in map arrows and a moved model
海流 (かいりゅう) means ocean current. 「地図に海流の向きを青い矢印で描いた。」 means “We drew the direction of the ocean current on the map with blue arrows.” The blue arrows represent the direction of the current on a map.
「探査船の模型を海流に沿って動かした。」 means “We moved the model survey ship along the current.” The moved object is a model survey ship. The sentence does not report an actual survey ship navigating or completing research.
Overlapping water meanings, different objects
潮流 and 海流 overlap in their water-current meanings here. The examples do not establish an exclusive short-current versus long-current division or unstated oceanographic criteria.
A ship's course, the course of society, map arrows and a moved model are different objects or representations. Read 社会の潮流 and 探査船の模型 without replacing social change with water movement or the model with an actual vessel.
What changes or moves in 社会の潮流を変えた and 探査船の模型を海流に沿って動かした?
Show the answer and why
Technological progress changed the course of society in the first, and a model survey ship was moved along the current in the second. They do not report society physically moving or an actual survey ship navigating and completing research.