In a word/acronym, RTOS. Its forest of O(1) algos and insane low latency reliable guaranteed response.
The joy of (hardware related) spinlocks and related contention control algos that non-embedded systems would resolve with the reset button and/or blaming the operator.
Mergers of a lot of classical engineering control theory and computer science (although not limited solely to embedded).
I don't think anyone in industry writes mathematically provably correct software except embedded aerospace.
As much as it pains me to say it, on a multidecade basis, exception handling and testing seems to be retreating to life-critical embedded work, even if in the rest of the biz those topics get a lot of PR.
I think they're writing about "real" embedded like the space shuttle autopilot as opposed to "its just a PC w/ PC app, but not typical PC hardware and outside a cubicle" like an asterisk appliance or a linux based small NAS appliance.