Yeah, they had a "server" Mac mini that was faster multi-core at the cost of being slower single-core. But 2011 Mac mini server https://everymac.com/systems/apple/mac_mini/specs/mac-mini-c... or non-server https://everymac.com/systems/apple/mac_mini/specs/mac-mini-c... vs the iMac https://everymac.com/systems/apple/imac/specs/imac-core-i7-3... of the same year, the iMac is much faster than both in both single and multi core.

I did have a 2010 Mac mini server, don't remember how it compared to the non-server one other than having dual HDDs instead of the DVD drive. I put them in RAID-1.