FY Time Characteristics in Controlling Cube

Hi

In one of our Controlling Infocube we have following Time Char's

InfoObject

Description

0FISCPER

Fiscal year / period

0FISCVARNT

Fiscal year variant

0FISCPER3

Posting period

0FISCYEAR

Fiscal year

What is the difference between Fiscal year / period and Posting period,Fiscal year.

I need to create a user entry variable,So that user can Select Posting Period & Fiscal Year

Please let me know how can i achieve this

Thanks