The difference between the Python interpreter you installed on your Mac and the Python interpreter used in PyCharm typically comes down to configuration and environment management. Here are some key points to understand these differences:

1. System Python vs Virtual Environment
   System Python: This is the version of Python that you installed system-wide on your Mac. It can be accessed from any terminal session and is usually located in directories like /usr/local/bin/python3.
   Virtual Environment: PyCharm often uses virtual environments for projects to isolate dependencies. A virtual environment is a self-contained directory that includes its own Python interpreter and libraries, separate from the system-wide Python installation.
2. Interpreter Configuration in PyCharm
   Project Interpreter: Each PyCharm project can be configured to use a specific Python interpreter. This interpreter could be a system Python, a virtual environment, or a conda environment.
   Virtual Environments: When you create a new project in PyCharm, it often creates a virtual environment in the project directory. This isolates the project’s dependencies from other projects and the system Python.
3. Dependencies and Packages
   System Python: Packages installed using pip install from the terminal (without activating a virtual environment) will be installed globally for the system Python.
   Virtual Environment: Packages installed using pip install when a virtual environment is activated are only available within that environment. PyCharm manages these environments to keep dependencies isolated.
4. Environment Activation
   Terminal: To use a virtual environment in the terminal, you need to activate it using a command like source venv/bin/activate (for virtualenv) or conda activate env_name (for conda environments).
   PyCharm: Automatically activates the project’s virtual environment when running scripts or using the integrated terminal.