Note that my title was incorrect.
(1) there are two distinct flaws (known as Meltdown and Spectre), and
(2) they affect most cpus, not only Intel (though some AMD and ARM cpus don't have both issues).
They are similar, though, as one is concerned with "speculative execution" and the other with "out-of-order" execution, both using the cache behaviour to find the contents of memory they shouldn't be able to. One enables access to the kernel, and the other access to other processes in the same machine (e.g. even other VMs if they are not fully virtualised).