The 'high level' driver is here
https://docs.mongodb.com/php-library/current/reference/
This extension is developed atop the » libmongoc and » libbson libraries. It provides a minimal API for core driver functionality: commands, queries, writes, connection management, and BSON serialization.
Userland PHP libraries that depend on this extension may provide higher level APIs, such as query builders, individual command helper methods, and GridFS. Application developers should consider using this extension in conjunction with the » MongoDB PHP library, which implements the same higher level APIs found in MongoDB drivers for other languages. This separation of concerns allows the extension to focus on essential features for which an extension implementation is paramount for performance.
The 'high level' driver is here
https://docs.mongodb.com/php-library/current/reference/