Barred Rock/Plymouth Barred Rock what's the difference?

[lulumammato2]

I recently purchased some Barred Rock chicks, the breeder was very clear that these were not Plymouth Barred Rocks are the Plymouths larger/do they lay differently?

 

[buffalogal]

Plymouth Rock is the breed, barred is a color variety. Plymouth Rocks also come in blue, buff, Columbian, Partridge, silver-penciled and white

Just thought; perhaps he means they are sex linked barred colored birds and not a "breed" at all?

 

[Buck Creek Chickens]

barred rocks are more common that other variety (color) of rocks, some do think the barred is a separate breed