Let’s talk a little about the V$ views and data dictionary views. The views store data while the database is up, when you shutdown the database you lost data, you can access some when the data base is in nomount or mount state. The data dictionary views do not lose any data but you can only access them as the database is open.
Usually, with some exceptions, the data dictionary views are plural names and V$ views are singular names.
HTH – Antonio NAVARRO