556

Hey there everyone, just joined the forum. I hope this question isn't a dumb one but I haven't got an answer for it. I know the difference between 223 & 5.56 but when I look to buy ammo online I often see the ammo lable listed as "223/556" so my question is which one is it? The ammo I have...

Just wondering if there are any places that 223/556 ammo can be preordered or if there is still some available. Thanks