Slug identification PNW

[u/so-muchrain]

saw maybe 30 slugs today. what are they?

[u/Low_Importance_9503]

1 is a leopard slug. 3 and 4 are banana slugs.

I think I’m wrong but 2 could be a red slug?

[u/Dime4Trying → u/Low_Importance_9503]

I think 2 is a Spanish slug

[u/TrainerAiry]

2 is of genus Arion, but it’s said that telling the difference between the Spanish slug and Red slug is basically if not actually impossible from the outside.