I'm not an expert on the internals, but virtualenv interactions feel more seamless. When you run poetry, it activates the virtualenv before it runs whatever you wanted.

So `poetry add` (it's version of pip install) doesn't require you to have the virtualenv active. It will activate it, run the install, and update your dependency specifications in pyproject.toml. You can also do `poetry run` and it will activate the virtualenv before it runs whatever shell command comes after. Or you can do `poetry shell` to run a shell inside the virtualenv.

I like the seamless integration, personally.