Number of cores?
"It delivers 18 E5-2666 cores for a total of 36 vCPUs – more than some versions of Linux can support."
I'm not sure what the limitation is there unless you are talking about 32 bit versions of Linux, where they often limit the number of cores to 8. Of course 32 bit servers are probably not that common these days (at least with Linux). On 64 bit server versions, 256 cores is a more common default.
If I recall correctly, the limit on number cores can be changed, but the distros usually set a default based on RAM usage (tables for tracking cores, if I recall correctly). A really high default number (e.g. thousands of cores) is possible, but it's less efficient on smaller systems.