Do both of them mean "difference?" Not sure if they are the same part of speech or if they are interchangeable.
Both 差異 and 差別 mean "difference"
差異 = (physical) difference
差別 = (physical or metaphorical) difference
这两张牌全无差異/这两张牌全无差別 (these two cards have no difference)
the two cards are physically the same
对我而言，有机食品和普通食品之间並无差别 (to me, there's no difference between organic foods and common foods)
the two products have the same food value to me
you cannot replace 差别 with 差異 here because the difference between them is not physical but of value in your opinion.
One more example for 差别 used to describe metaphorical difference:
输给彼得或输给保罗是一样的，没有什么差别 (lose to Peter or lose to Paul are the same, there's no difference)
the main point is you lose
Again, you cannot use 差異 instead of 差别 here because the focus is not on the physical difference between 'lose to Peter' and 'lose to Paul' . The focus is on the win or lose result)
In addition to Tang Ho's answer, one of the major difference between these 2 words is:
差異 is usually used when measurement is involved.
Say if you're comparing the weather between 2 countries:
- The weather between Canada and Africa differ greatly
- The temperature between Canada and Africa differ greatly
Note that some of the metaphorical differences (as mentioned from Tang) might not be as 'measurable', such as culture, knowledge, etc.
simple to say
差異 = difference; divergence; discrepancy; diversity; odds; variation
气候差异 difference in climate
文化差异 cultural diversity
看法上的差异 difference of opinion
差別 = difference; division; distinction
缩小城乡差别 narrow the gap between town and country
年龄差别 difference in age
质量与数量上的差别 qualitative and quantitative differences
你去不去没什么差别。 It makes little difference whether you go or not.
refer dict： https://www.jayxun.com/what/7AJv