They are complaining of disparities in pay, conditions, and promotion prospects.他们在抱怨收入、工作条件以及晋升机会上的差距。

their disparity in age and lack of any real common ground他们在年龄上的差距以及真正共同点的缺乏

There are wide disparities in living standards.生活水平的差距很悬殊。