I.X.
eastern king wider and shorter
ca king narrower and longer
one is not better than another per say. Ca king better for tall people. Also, they have a more attractive proportion as they are slightly rectangular and the ea. king is more or less a quare. I don't know if this has anything to do with living in CA, but its way easier to find Ca king sheets than standard sheets.
I own an eastern king because I didn't think it made sense for my 5'-4" frame and my husband 5'-11" frame to buy extra long mattress. We are not tall. We did however like the idea of the whole family snugging in the wider bed. So we stuck with ea king.