Nowadays candela and candlepower can be considered as being equivalent.
Historically there was a minimal deviation.
The candela has become the official unit. Yes, it’s a good unit for measuring throw.
candela (luminous intensity) measure the total of light which is emitted by the whole device (including reflector or lens)
in a very specific direction (we’re interested in the spot direction).
There’s no difference among source types like HIDs, LEDs or hot wires, it’s just about the light.
And in a certain distance this luminous intensity then results in a certain illuminance,
measured in lux (the further away, the less lux).
But in a distance of 1 meter (~3ft) the numerical value is the same: 1 candela produces 1 lux in one meter distance.
That’s why you often read something like “light has 300,000 lux” while it’s strictly speaking 300,000 cd.
Everybody knows what is meant, but here DrJones explains why candela could be preferred.
lumen (the luminous flux) in contrast measure the total of light which is emitted in all directions, added up.
Both units, candela and lumen, are very useful, but they mean completely different things
and you need both to get at least an idea of the actual beam.
Dragster throwers often optimize candelas and sacrifice lumens :- ) when the spot is very bright (many lux) but tiny (few lumens).
The unresisted exaggerations of candlepower numbers for big hardware store lights are just, mhh, best practice:
It’s “US-hardware-store-CandlePowers” just like it’s China-lumens for some vendors.