Data center proxies come from servers in data centers, while residential proxies come from real people's connections. Static proxies mostly come from data centers, while rotating proxies are residential, although there are exceptions for Residential proxies.
Both IPv4 and IPv6 addresses can supply static and rotating proxies, but static IPv4 proxies may be harder to come by since they've all been assigned. IPv6, on the other hand, has trillions of available IP addresses.