Mhhh dunno. They do look similiar tho Lilly's face is slimmer and her eyes always have that sad or mad expression while Carley's face is much wider and her eyes express constant suprise imo.
I really hate what they did to Carley in Episode 1 with the radio. I like her but the fact that in EP1 she didnt check for batteries, then placed them wrong, and also mentions that she doesn't know what batteries look like (when you search for them), made her look really really utterly retarded which doesn't fit with any of her other characteristics.
As for Lilly's job:
http://labor.alaska.gov/research/dlo/mechadm.htm
She mentions it when you ask if she is a pilot in the air force.