As noted previously, XPOZ scripts can invoke other XPOZ scripts. The difference between an .xpoz and a .env script is that the .env script does not generate a new execution level. Otherwise, these environment scripts behave like regular XPOZ scripts and are used to define the environment needed to run the rest of the script.
Often, the .env file can be thought of as a test wrapper. It sets up a test environment, places values on variables used by multiple test scripts, and then invokes a series of test scripts. Using .env files in this manner allows for easy combination of test script files without setting up the test environment for each test script.