When you sync from Huawei Health to Strava, the distance will always be different. Sometimes the moving time will be different also. Strava calculates this kind of data itself, based on the GPS data. Huawei Health calculates the distance and active time not only on gps data. This is why there is a difference. You can read more about this on the Strava support site:
To get the most accurate data in Strava, please make sure that you start the activity tracking with your Huawei wearable only when the gps signal is received. Else the first part of your activity will be without gps data. This will result in a shorter distance in Strava.
Also make sure to keep the phone screen on while the sync is active. You don’t have to keep Health Sync open. But you have to keep the phone screen on until the sync is done. Huawei does not allow reading data from Huawei Health when the screen is off or locked. So when the phone screen is turned off while synchronization is active, some of the GPS data cannot be read and cannot be synchronized. This will result in inaccurate data in Strava.