一概而论 (yí gài ér lùn): to lump different matters together (idiom)

Although both cities are coastal, their climate, culture, and lifestyle habits are very different, so they cannot be lumped together.

International students come from different countries and have different academic backgrounds; teachers cannot treat them all the same and should guide each according to their individual situation.

Although this company's products are cheap, their after-sales service is very good, so you can't say that cheap goods are always of poor quality.

Regarding online shopping, some people find it convenient and affordable, while others worry about quality issues; both views have merit and cannot be generalized.

Although the exam questions were relatively difficult this time, each student's level of effort was different, and their scores varied greatly, so one cannot make a blanket statement.