Growth habit & rate: Black Diamond vs Columbia Star
I love the stocky growth habit of Black Diamond but can see it as a disadvantage for many. It works good in a 3-5 gallon pot. Columbia Star has the normal long canes of other trailing western blackberries. Both are thornless.
The BD was planted a month earlier than CS, both in-ground. BD has one cane about 6ft long vs four canes totaling ~25-30ft for CS.