Meltdown is a Variant of Spectre this isn't how Intel classifies it, this is how Google Project Zero, and heck even Intel's competitor AMD classifies it.
It's also not the scariest variant, it's easily fixed (performance degradation aside), doesn't require a microcode update to be fixed hence is 100% software mitigated, doesn't allow you to cross between guest and host memory address spaces and isn't remotely exploitable.
On the other hand variant 1 and 2 are much scarier because they are the complete opposite of Meltdown.
https://www.amd.com/en/corporate/speculative-execution
https://googleprojectzero.blogspot.co.uk/2018/01/reading-pri...
It's also not the scariest variant, it's easily fixed (performance degradation aside), doesn't require a microcode update to be fixed hence is 100% software mitigated, doesn't allow you to cross between guest and host memory address spaces and isn't remotely exploitable.
On the other hand variant 1 and 2 are much scarier because they are the complete opposite of Meltdown.