So we've been talking about this in Philosophy class but we don't have time to really talk there so here you go.
The gyrencephaly index of orca brains is 5.70, more than double that of humans (2.2). That basically means that their processing speed is faster than that of humans, and they can handle more data, which is really helpful in the oceans.
They also have a really highly developed paralymbic system and amygdala. The first is for spatial memory and navigation (again, really helpful in the oceans). The second relates to long-term memory and emotional learning.
They appear to mainly process information through audio. Water is a great transmitter of sound, so that makes sense.
There's about 40 sounds in their language, but they vary so much in intensity and tone, so they might very well be used in a very complex language.
Ravens are believed to have an intelligence of the average 7-y-o human. Also, deciding how intelligent animals are is kind of stupid since they seem to do well in their environment. If we try to live in the sea, we'd drown. (also intelligence is such a stupid thing to compare and tie worth to anyways, but that's a different discussion)
Orcas are so fascinating, they're one of my fav animals ! Each time I learn something about them, they impress me even more.