成績 and 点数: performance and scores
Distinguish performance across activities from numerical scores.
An evaluation of performance
成績 (せいせき) refers to performance or evaluation results in study, sports, and similar activities. 「今学期の成績が上がりました」 says that this term's grades improved.
It also describes work performance, as in 「営業成績」, sales performance. Limiting 成績 to a single school test score would miss that use.
A numerical score
点数 (てんすう) refers to points awarded in an assessment. 「試験の点数は八十点でした」 means that the test score was eighty.
「点数を計算しました」 means calculating the score. The calculation alone does not reveal whether the score was high or sufficient to pass.
One score and an overall evaluation
「今回の点数は低かったですが、学期の成績は悪くありませんでした」 says that this score was low but the term's grades were not bad. Different assessment scopes allow both statements to hold.
「成績表をもらいました」 means receiving a report card. Distinguish the document from its scores; receiving it does not imply improvement.
Does 「点数が高い」 guarantee a pass?
Show the answer and why
No. It describes a high score; the pass criteria and actual outcome must be checked separately.