Perdition City is kind of like this girl you like that have a pretty classy lifestyle, she's wearing a red dress sometimes during the weekend and drinks a bit too much at parties but you like her anyway while Blood Inside is more like the girl you've never really talk to because you're shy and is pretty casual with her friends but you feel like asking her out would scare her because she's not super social in general but everyone says she's quite good in bed.
That being said, I feel like Perdition City has two different half, but it flows very well. You really need to be in the mood for it. I love listening to that album at night, when I'm driving for example. Blood Inside is just...it's something else, really. I've never heard anything like that. It feels like a journey. The diversity, the moods, the sounds...it's beautiful.