DBT is basically a category of CBT. "It’s based on cognitive behavioral therapy (CBT), but it’s specially adapted for people who experience emotions very intensely."
This is why it's often recommended to people with PTSD who fit this (or similar) criteria, among others.
(I've never heard of IFS, but I studied in Canada so some things don't cross over.)
IFS = Internal Family Systems. I don't think it's very big at least right now. I think it's also recommended for PTSD. To me it feels more in line with psychotherapy in that it looks at root causes, whereas CBT is more of a surface level thing. DBT seems somewhere in between.