I have no experience with either.

But a very quick Google showed me that Nordic is 1) a male clone and 2) extremely hardy for an inkberry (zone 4 or colder!).

Shamrock is a female and is likely not quite as hardy.

Both are compact and supposedly have a reduced propensity to send up suckers. they are likely about the same size.

I'm sure more info and differences would come up with a more extensive search.

This post was edited by dave_in_nova on Sat, Nov 1, 14 at 9:37