It's the same board software; that's why they look vaguely familiar in format (phpBB is extremely popular free, Open Source board software and is probably the most widely used board software on the internet, so you'll see it everywhere).
I'm a member, and was one of the two original moderators of that board. I stepped down, and set this one up when that one was yet again, offline for several weeks -- as it has been several times as the admin does not participate on his board, can take a long time to fix problems, and as he doesn't always update the board software regularly, the board has been hacked and taken down a few times in the past two years. He was also very hard for moderators to contact. These things were frustrating to me at the time (now, he has enabled the moderators to do some admin tasks).
Also, I wanted to actively encourage a more international community (not least as the breed is originally from England and is the single most popular toy breed in the UK and Ireland, where the breed is very common!
) as so many sites are very US focused. And I wanted to be able to add forums as I wished, allow people to use avatars, add a wide range of smilies, and add in modifications that protect the board against spam and other problems. Setting up and managing this board myself enabled me to do all these things, thus Cavaliertalk was born (I think you mean Cavaliertalk and not cavalier chat?).
I am closing this thread as I don't really want to expand on the differences and it isn't considered good board netiquette to discuss other boards or lists but as you asked, I wanted to give a small bit of this board's direction and history. Several boards in addition to these two are out there, each with its own personality and ethos and focus and some targetting a specific country, as are at least a dozen email discussion lists on cavaliers.