PHP-Deno provides deno_core and deno_runtime bindings for PHP, via a PHP module. This allows users to run JavaScript in a V8 Isolate, via the Deno runtime. The extension provides wrappers for deno_core, which is a low-level wrapper around V8. This can be used to provide a secure, sandboxed environments to execute user scripts. The higher-level deno_runtime wrapper is also provided, which includes the V8 Isolate, the Deno.core.* API and web apis (such as fetch, TextEncoder, etc) to JavaScript modules and scripts.
This project is similar to V8Js in that it provides PHP bindings to a V8 Isolate, however it does this via the Deno project. It's analogous to embedding Node in PHP, rather than solely V8.
PHP-Deno also includes a PHP <-> JavaScript bridge, to expose PHP functions to JavaScript. This is achieved via the Extension class.