What is the difference between Contract driven testing and behavior driven testing

I cannot differentiate between the CDT and the BDD. The contract testing seems like giving some request and verifying the response. So what are the differences between CDT and BDD?

What's the point of having a "pact server"? We are defining the kind of object we expect and making an actual API call to the provider, which I believe is what we can do without using pactjs as well and what seems like we have been doing in BDD.