openssl – difference between passphrase (-k) and key (-K)?

I’m using openssl for a project and came across two options: -k passphrase and -K raw_key (hex). What’s the difference between the two options? I’ve been attempting to port something from openssl to Python, and the openssl command I’m using for my basis uses -k (32-bytes_of_hex_data), which yields an entirely different key is I use the -p switch to see the key being used.