voltage regulator vs dc dc converter
There is a great video on youtube. In short, if you have a high current output you should take buck converter, for lower current a voltage regulator is the better choice. Why? A buck converter has a greater efficiency when the current is "high" but it's lower then the voltage regulater efficiency when the current is low. 


  The linear regulator has a much cleaner output voltage than a buck converter in most cases. So if your circuit is sensitive to changes in the input voltage a linear regulator may be better.


comment from youtube.