Most faces are pretty much identical to the models they were based on.. ex: MaleShep, Jack, Liara, Samara...
But with Ashley... I don't know, they made many changes. The eyebrows and lips are too fucked up.
One thing too is that the face model for Ashley made changes on her face too. Erica's nose, especially, it wasn't cute and small like it is in this pic.
Ashley could have got some upgrades herself too.