Is there a difference between inactive accounts and dormant accounts?,are they the same or there is a difference related to their period of inactivity?

Dormant status is a matter of policy and in some instituations an account can be "inactive" for years before being classified as dormant. Once an account is classified as "dormant" there is generally more detailed attention paid to a transaction that would impact the account.

Your state may also have defined these terms. Cross check state used definitions against your deposit agreement. Texas, as an example doesn't use the word "dormant" in our code.