Mysql的查询

这是数据库的内容和题目要求

1：
select max(Salary) SecondHighestSalary
from employee
where
salary<(select max(salary)from employee)

2:
select max(Salary) SecondHighestSalary
from employee
where
salary<(select max(salary)from employee)<(select min(salary) from employee)

这两种查出来的结果不一样，是哪里有区别，原因又是啥？