Size
The Standard Schnauzer is a little larger on average: about 17 kg (37 lb) as an adult, against 14 kg (31 lb) for the Kerry Blue Terrier.
Shedding
Their coats shed differently: the Kerry Blue Terrier sheds through the year, the Standard Schnauzer holds loose hair until it is brushed or clipped out.
Grooming
The Kerry Blue Terrier needs more grooming, brushing a few times a week, where the Standard Schnauzer needs a brush once a week.
Temperament
They differ most on independence (Kerry Blue Terrier: decides for itself; Standard Schnauzer: cooperative, with its own ideas) and on prey drive (Kerry Blue Terrier: likely to chase small pets; Standard Schnauzer: chases; needs managing).
Alike
Both are rated the same on loyalty: sticks close to its people.