Difference between different deleting options and emp id

Hi,

There are 3 ways in which we can delete emp ids

T-code PA30

T-code PU00

Through report RPUDELPN

Query: What's the difference between the 3 and what is the impact on the system

Also if I have an internal number assignment i.e. personnel id is generated internally than how would each of the above options impact the sequence of emp id.

Will either of them result in system assigning a deleted personnel id to a new hired employee.

RB