The fuel in a turbine engine is metered by a fuel control unit, there is a mixture but it's based on throttle position, various pressures, and RPM.
Hydromechanical fuel controllers, like in older jets don't include protection for things like over temp, overspeed, stall etc.
Electro/hydromechanical, like in the good old CRJ-200 may have some of those protections or not, and may have some features like the CRJ's N1 speed control.
FADEC gives the computer full control over everything.
That's it in a pretty small nutshell.
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