Difference between pip3 and python3 -m pip

They are the same. If you look at the pip3 file in the bin folder it calls the main function from the pip module.

pip3 install package_name runs pip3 file in the bin folder:

# bin/pip3 
# or bin/pip if using pip install package_name

import re
import sys

from pip import main

if __name__ == '__main__':
    sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0])
    sys.exit(main())

python3 -m pip install package_name runs the __init__.py file of the pip module.

# pip/__init__.py
if __name__ == '__main__':
    sys.exit(main())

Both of them run the same main() function