What I got with Recovery Disk Assistant? Environment:


Mac Mini Mid 2010. Original OS is Snowleopard
Current OS is Yosemite
Tool. Recovery Disk Assistant which is downloaded from Apple website.


Purpose:


Make a recovery Yosemite disk on USB stick


Procedure:


Downloaded Recovery Disk Assistant fro Apple
executed Recovery Disk Assistant on Yosemite


Problem:
  The recovery disk assistant has fixed image and text. There is a Lion photo image, not Yosemite and it said successfully made Lion recovery disk.

So I am wondering whether I got Lion recovery or Yosemite recovery...
Yes, it is a Yosemite recovery USB flash drive. The application copies the hidden (internal disk) recovery partition to the flash drive. I believe Apple no longer recommends using a recovery flash drive, so I suppose they have not updated the Recovery Disk Assistant application. I believe Apple now wants you to keep a bootable copy of OS X on an external drive. Still, the recovery flash drive is good to have if you need to download and install a fresh copy of OS X (and your internal recovery partition is damaged). Some will argue you can just boot using internet recovery to reinstall OS X, but you will get the version of OS X that was shipped with the machine. If you keep your flash drive up to date, then you can download the current version of OS X (that you have installed).