Do environment variables distinguish system environment variables from application environment variables?

Do environment variables distinguish system environment variables from application environment variables?
Or is it just a system environment variable?

Edit-01

my scenario is in Linux.
btw, does it have anything to do with the operating system?

There is more than one way for a POSIX host to create a child process.
One of them is
execle.

Note the envp argument.

An interactive shell, such as
bash,
can export a variable, or not.
Non-exported variables are uninteresting, they are not environment vars,
as they will not appear within envp.

You were wondering if there is a sys vs app distinction for env vars.
There is no such distinction.
Either a key=value entry appears in envp, or it does not.
If it does, then it is an env var. If it does not, it is some local setting
of interest only to the environment where it was assigned a value.
Fork a /usr/bin/env child if you want to see current env vars.

Another way is execvpe.

And yes, I know, the typical pattern is fork() and then exec.
Though BSD and others have experimented with variations on
that theme, to avoid expensive fork work which exec immediately
discards.