What is the difference between
ViewsLifeTime managed properties ?
These properties are maintained by SharePoint Analytics and can be used via CSOM or Search Queries.
ViewCountLifeTime - This is a special managed property that is not associated with any crawled property. This property shows how many time a document has been viewed on the office web apps.
ViewsLifeTime - This property data is updated every 15 days and give you the view count for content (Ex: Page/Site etc)