Is there a difference between "f" and "F" in Python string formatting?

Question

To format strings in Python 3.6+, I usually use the lowercase "f" option to include variables. For example:

response = requests.get(f'{base_url}/{endpoint}?fields={field_list}')

I've recently seen one of my coworkers who always uses capital "F", instead. Like this:

response = requests.get(F'{base_url}/{endpoint}?fields={field_list}')

Is there a difference between the lowercase "f" and capital "F"? And if yes, when would you use each?

Answer 1

As explained in the PEP 498, chapter Specification, both are accepted, and should not differ.

In source code, f-strings are string literals that are prefixed by the letter 'f' or 'F'. Everywhere this PEP uses 'f', 'F' may also be used.