anaconda – python versions (conda -forge)

I am using 18.04 Ubuntu with Anaconda.Recently i have trying to install OpenCV through conda-forge channel in the base environment. I did not install purposely any Python version and did not use any pip command either in base environment. Now, in the base environment, if execute just python, i get the same python version as system version and if execute python3 , i get the version installed by conda-forge. Please refer the screen shot. Python_on_Conda_base

I would like to know what is difference between python and python3 command?.What is should i keep in mind? basically i prefer the version 3.7.5 Python
.So, only the Python3 has uses different version. So, question what i should take note when i using python3 some_script.py? what is pros and cons of having this 2 version?

So far,i did not face any issues, but removed the conda-forge channel from Anaconda to avoid any conflicts. Any thoughts?
After posting this question, i have noticed python --version command gives Python 3.7.5 on Conda base environment and Ubuntu terminal (outside Conda)