Difference I have been told between 14% & 12% is mainly corn, a waste for mini's. Both are a complete feed like Omlene and very compareable. A lot of people like Choice, a little cheaper but a pellet feed.
They also are developing a mini-feed; over due to be released on the open market. I ran into the same problem with suppliers & now use Nutrena. Pick a feed and stick to it; whatever one you choose! Whether you own a Ford, Chevy, or Dodge(etc.); you will always find pros & cons; likewise in feed. Watch your minis close and they will tell you when a feed does not fit YOUR MINIS! Not all feed fits all minis but the major feed suppliers usually sell closely formulated feeds.
Different parts of the country substitute locally grown crops to get the same chemcial balance in the feed.
Sort of like the difference in "Hay" you hear about around the country.
GOOD Luck!