DIFFERENCE BETWEEN RANK() AND DENSE_RANK()

I have the following table
 
Employees
 

 

I need to arrange them in order of their seniority. Their are two ways to do this. In the first case we use the RANK() function

 

select empid, empname, age, RANK() over (order by age desc) as Rank 
from [dbo].[Employee] 



 

 

select empid, empname, age, DENSE_RANK() over (order by age desc) as DenseRank 
from [dbo].[Employee] 

 

 







If we notice the difference, the first result set doesn't have rank 4. The reason if to people have the same rank, DENSE_RANK() gives the next immediate rank whereas RANK() doesn't. Hence Jack has a rank of 4 via DENSE_RANK() but 5 via RANK().