Fiscal year variant determines if you are using calendar
dependent year or year dependent (where you can create your
own periods) eg you want your period 1 to be April period 2
to be May and so on.
Posting period determines which period is open. Your company
code is tied to a posting period variant. Each posting
period variant is tied to an account type (G/L, vendor Asset
etc)
Here you determine if period 1 should be open or period 2 etc.
Fiscal year variant and Posting period variant are
differentiated based on their purpose. While fiscal year
variant is to define no of posting a period allowed and is
assigned to co code, posting period variant is to decide
which periods can be opened at particular point of time for
posting. Separate rules can be defined for each type of
account. This is used for control purpose.
There isn't relation between Fiscal year variant and Posting
period variant. But there is relation between Fiscal year
and Posting Periods. Fiscal year structure contains posting
periods. For each posting period we have specified day end.
To process business transactions these posting periods must
be in open status. You can open all the posting periods (or)
you can restrict the posting periods by Account Type wise
and Account No wise and Authorization group wise.