Bathroom door knobs are considered privacy door knobs. This type of door knob is designed for interior use, rather than an entry way door knob.
Privacy Door Knobs
Privacy door knobs are different from exterior door knobs because there's a lock on one side and no key entry on the other. The lock can be a lever or a button in the knob. Some door knobs require you to flip the lever to unlock the door, while push-button door knobs typically unlock automatically when you turn the inside door knob. Some knobs have a button in the center that you twist and either untwist to unlock, or turn the door knob to unlock.
If you have small children or people in the home who might have trouble turning a lever or twisting a small latch, then a door knob that unlocks automatically when turned is the best choice. You can also choose a lever –style door knob that unlocks automatically when the handle is pushed down.
You may also want to purchase bathroom door knobs that have a tiny hole in the middle of the outer door knob. This hole allows you to insert a nail or another small long object. By moving it around just right you can unlock the door from the outside in case of an accidental lock-out.