A fingerprint is harder to fool due to most being captured at a higher dpi / resolution than a standard camera allowing for a more accurate capture to compare real fingerprints against.
A facial recognition algorithm has to leave a little wiggle room due to how your face naturally changes; dry hot weather causing dry skin, cutting yourself shaving, getting a black eye from falling off the bed ...
Your fingerprint on the other hand is much more resilient.
At work they made us scan 2 fingers just in case "something happened" to the other finger.
There is no second face you can scan lol.
Notice earlier I said harder to fool not secure.
Both can be easily fooled
Mythbusters did an episode solely on getting past a fingerprint biometrics.
https/www.youtube.com/watch?v=3Hji3kp_i9k
As for the facial biometrics you may not beat it with a mask but with a specially made image on a computer screen with the iphone being forced to believe it was a real person.
A 4k picture of some one from lets say instagram is enough to start the building of an image to fool a facial scanner.
It is a lot harder to get a high resolution of a finger from social media, unless some one frequently posts high resolution pictures of their finger lol.