Crawl space encapsulation is a generic term used to describe a crawl space that is protected from moisture by using a vapor barrier on the floor and walls. In other words, encapsulation refers to sealing up your crawl space and keeping the moisture sealed outside. This term was and is widely market by different basement waterproofing franchises in the early part of the century.

See the evidence showing the differences and similarities in the 20 mil CleanSpace and 20 Mil SilverBack crawl space vapor barriers...

What is an open crawl space and why does it need to be “fixed”? A typical open crawl space has open foundation vents and an exposed or partially covered dirt floor. Open Crawl Space​This type of foundation construction is very common throughout the United States and Canada....