A route described as moderate in one country can involve exposure and scrambling that the same word would never imply in another. Grading systems are national conventions rather than a shared scale.
Each system grades a different quantity
Some national systems grade primarily on technical difficulty of the terrain, describing what the hands and feet must do rather than how long the day is.
Others fold in effort, distance and ascent, so a long but easy route receives a higher grade than a short technical one.
A third approach grades on consequence, weighting exposure and the seriousness of a fall above the physical difficulty of the moves themselves.
Alpine systems assume mountain competence
In many Alpine countries the grading baseline assumes a walker who is comfortable on steep ground, can handle a cable-protected section and understands basic mountain weather.
The middle grades therefore include terrain that a lowland walking system would classify as scrambling or would not describe as a walking route at all.
Cable-protected routes have their own separate scales, and those scales measure exposure and sustained effort rather than technical hardness.
Waymarking carries information the grade does not
Paint blazes, cairn systems and signpost colours often encode route seriousness locally, and the code is usually posted at the trailhead rather than on the map.
Some networks state expected walking times on signs instead of distances, calculated for an unladen walker in good conditions.
Those times are useful precisely because they are consistent within a network, but they translate poorly between countries where the reference walker is defined differently.
Seasonal state changes everything
A grade almost always describes summer conditions on dry ground. The same route with snow on it, or with a swollen stream crossing, is a different undertaking.
Late-lying snow on north-facing slopes persists long after the valley looks clear, and it is the most common reason a graded walk becomes unsuitable.
Local information offices and refuge wardens track this and update it, which makes them a far better source than any printed grade.
How to translate between systems
The reliable method is to read the route description rather than the grade, since descriptions state exposure, scrambling and stream crossings explicitly.
Ascent in metres and total distance together predict effort better than any single letter or number, and both are usually published.
Comparing an unfamiliar route to one already walked in the same country is the only translation that works, because it holds the grading convention constant.