Not an expert here, but given the differences in measurement scales, I suspect there is a difference in intensity.
If my reading of this Hong Kong Observatory reference is correct, a no 8 is classified as wind speeds between 63-117 km/h.
When we talk about hurricane strength, we’re using this scale. Unless they are measuring different metrics, a no 8 is the equivalent of a tropical storm. Which is to say, we don’t even rate that as hurricane strength.
Helene hit land at around 220 km/h (Cat 4). Milton reached speeds of 260km/h (Cat 5), but might weaken to 190-200km/h (Cat 3) by the time it reaches land.
No. 8 is just one of the signals. There are also no. 9 and no. 10. These signal are used based on the wind speed at HK instead of the storm itself.
For the actual strength of the typhoon, we just call them differently: https://www.hko.gov.hk/en/informtc/class.htm
Although I’d admit the current hurricane is actually stronger than a lot of typhoons: https://www.hko.gov.hk/en/informtc/historical_tc/metinfo_wind.htm
