getenv() vs. $_ENV in PHP

Question

What is the difference between getenv() and $_ENV?

Any trade-offs between using either?

I noticed sometimes getenv() g

Answer 1

I found getenv() useful to avoid a strange PHP bug where sometimes $_SERVER and $_ENV was undefined if auto_globals_jit was enabled (creating the _SERVER and _ENV variables when they're first used). Since then I began to to use it.