Cute chicks
O.K.
I see 5 of the Barred birds - it's hard to tell the breed from the photos, they could be Plymouth Barred Rock, Dominique or Cuckoo Marans - these would be "large fowl".
The 3 Buff Colored ones, it's hard to tell the breed from the photos as well, they could be Buff Orpingtons, Buff Rocks, or some other breed of buff colored bird - these would be "large fowl" as well.
"Bantam" is a term used to describe the size of the chicken - a bantam would be small. While some of the breeds that you have can come in "bantam size", they look like they will be full or "standard" size - which is considered "Large Fowl"
"Breed" is a term used to describe the particular breed of the chicken - "White Leghorn" is the breed of the white ones that you have (some look like boys (cockerels) too
The birds that you have - will be large - depending on what breed the barred ones are they could be anywhere from 4 -6 lbs or so. The Buff ones - again depending on breed could be 4-7lbs or so. Leghorns will weigh around 4lbs. Bantam size hens weigh much less and are much smaller - some weighing in around 28oz ( less than 2lbs) some can be even smaller than that.
Makes sense?
Anyway - Do you have your coop and run ready? They will get big fast - they look like they are big enough to get into their coop and run
