主張 and 提案: advancing a position and proposing action
Compare a position supported by grounds with a proposal to extend break time. Separate making a proposal from the example of revising a schedule based on one.
Expressing a position
主張 (しゅちょう) means a claim or position. 「会議では根拠を示しながら自分の主張を述べた。」 describes stating a position while presenting grounds.
「双方の主張が食い違い、話し合いは長引いた。」 says conflicting positions prolonged the discussions. It states that the claims differed, but does not supply a new course of action.
Putting forward a course of action
提案 (ていあん) means a proposal or suggestion. 「会議で休憩時間を延ばす案を提案した。」 says a proposal to extend break time was made at the meeting.
「彼女の提案をもとに予定表を作り直した。」 says the schedule was remade based on her suggestion. Unlike the first example’s proposal alone, this also states an action taken on the schedule.
A position and a proposal can coexist
Identify a position about what is right separately from a proposed course of action. A proposal can contain claims or supporting grounds, so these words are not mutually exclusive.
Proposing a longer break does not establish that the break was extended. Implementation must be read from separately stated actions, such as remaking the schedule.
What course of action is proposed in 「会議で休憩時間を延ばす案を提案した。」?
Show the answer and why
Extending break time. The sentence states that the proposal was made at the meeting; it does not state that the break was extended or the schedule remade.