What is the difference between the 80265 and 80268 ammo besides the price?

From memory, one is .223 Remington and one is 5.56 NATO.

I could be wrong.  

Archived thread:

http://www.ar15.com/archive/topic.html?b=3&f=16&t=273239

From that thread:

There are 3 types with a 75 gr bullet,

#80268, comes in a black box with a black, nickel-coated case, and is loaded to .223 pressure.

#80265, comes in a red box with regular brass cases, is also loaded to .223 pressure.

#8126N, comes in a red box with brass cases, and is loaded to 5.56 pressure.

#80265 is loosely considered "LE" and #80268 is considered "civilian", although I think you can buy all of the #80268 you want from Hornady dealers. The consensus seems to be that there is no difference between the two. The #8126N is only drop shipped direct from Hornady and they will ask for your LE ID before selling it to you. FWIW, #80265 and #8126N is the same price if you order from Hornady.

The 5.56 TAP can be bought by "civies". Just not from Hornady. I have several local sources that never ask me for any ID. By the way, i aint sharing.

The 5.56 is great out of my 10.5". Not quite as accurate as BH MK262, but a couple hundred FPS faster. IMO, 5.56 TAP is the best heavy OTM for very short SBRs.