How they're calculated
When viewing the Landing Page asset in either Design Studio or Marketing Activities, the statistics section provides information regarding page views and form fill outs, if the page has a form located on it.
Difference between calculations
The difference between these two metrics is that the page views will keep a historical record of visits to the page. This means the total will not change if you happen to delete a bunch of records that visited the page in question - the total persists regardless if the record is no longer in the database. With that said, the forms section does not. This area is tied specifically to the existence of that known record in your database. This means that, once a record who filled the form out is removed from your database, the submissions they performed will be subtracted from the total.