LM317L VS TL431

http://www.ebay.com.au/itm/NEW-10-x-LM317LZ-LM317L-Voltage-Regulator-0-1A-TO-92-/330593378844?pt=LH_DefaultDomain_0&hash=item4cf8e6a21c

vs

http://www.ebay.com.au/itm/TL431-TL431A-Adjustable-shunt-regulator-2-5-to-36V-NEW-Qty-10-/111006289168?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item19d87d8d10

Give me an example where you'd use / prefer to use ONE over the other?...

..download the datasheets - there are examples in it.. :wink:

I looked at the data sheets

The TL431 prevents the output from going to a voltage too high for the "adjustable zener".
The LM317 prevents the output from going too low.
They have opposite functions. A load pulling current down from a TL 431 will not have a regulated voltage, but an LM317 will regulate the voltage when a load pulls a current down from the output. The TL431 is a negative regulator. The LM317 is a positive regulator. Neither one will set a voltage source which keeps a steady voltage when the load pulls up and down from the desired voltage.