Phone: Had a great hour long conversation with a researcher about previous experiences, plus some technical questions. Onsite: Most interviewers seemed fine, but definitely had a weird experience overall. One interviewer came in 10 minutes late, clearly had not read my resume (and was not interested in reading it even when I offered him a copy) and asked me technical questions that obviously were totally unrelated to my experiences. I'm sure they do great work but based on the experience things seemed somewhat disorganized. Also definitely felt like some people had big egos. That being said, your mileage may vary since I only did 4 one hour interviews plus lunch, and maybe I just had a bad interviewer or two.

Mostly discussed my past research experience with multiple staff scientists / scientific associates. They also asked a couple of hypothetical questions that are somewhat related to my research projects, and shared information on their own projects.