There are 3 identification features to look for when separating these two species..The links and pics below show them in good detail if there is any doubt in any of these then they should be recorded as
Copper underwing agg

This blog has been set up so local people can find out what is going on in the world of Moths, Butterflys and dragonflies in Calderdale.If you have any ID problems put up your photo's and someone will try and help you to id it.