What are the Differences Between Using $_ and $user in PowerShell Loops?

Yeah, they're functionally similar. But in the second method, since you're assigning `$users` from the CSV import, it lets PowerShell handle the whole collection at once, making it easier to iterate. If you're running the same command repeatedly or if you're working with larger collections, I'd say the foreach loop is often preferred.

The difference comes down to the type of `foreach` you're using. The first example employs `foreach-object`, which uses the automatic variable $_ for the current item in the pipeline. The second example is using the standard `foreach` loop with a predefined variable `$user`. Generally speaking, in Windows PowerShell, the foreach loop is typically faster than foreach-object due to lower memory overhead.

The first is better when you want to keep working with the pipeline, while the second is preferable when you want to manipulate all the items as a complete collection.

You're right—both forms can achieve the same task, but I think the second form is more readable and easier to debug. Plus, you don't have to deal with using the automatic variable. Instead, you can just reference `$user.UPN`, which is clearer. Also, using `foreach` could save you some performance, especially with larger datasets.

Both work, but I'd caution that you're using the second example incorrectly—it should be `$users = Import-Csv ...` beforehand. In terms of speed and resource consumption, the plain `foreach` is generally faster than the pipeline counterpart. Think of your use case: if items are already in memory, go with `foreach`; if they need to be streamed from a cmdlet, prefer `ForEach-Object`.

They are effectively the same when accessing properties in the loop: one uses automatic piping with `$_` while the other uses a custom variable. For larger collections, `foreach` tends to be faster since it's not reliant on pipeline processing. The clarity offered by `$user` can often make maintenance a lot easier `if you ever revisit the code later.