Inductor through hole legs different length
Sometimes the properties are a bit different depending on mounting direction. From the murata website (https://www.murata.com/en-us/products/emiconfun/inductor/2012/05/14/en-20120514-p1):


  If the inductor structure is not perfectly symmetric, properties will
  change with the mounting direction. We therefore leave a mark so that
  the user will know the inductor has directionality. That way, when
  they use the inductor, they can hope to make the fullest use of the
  intended properties.




Also it can be useful to know the polarity to understand the direction of the magnetic field that will be induced. If a lot of inductors are used close to each other, their fields will interact.