Apple Watch and Health App steps count do not match and have changed

I have been experiencing a problem with my Apple Watch and Health App steps count not matching by hundreds. Further to this, screenshots of the data have changed over the last weeks while I was in a different time zone on holiday. Surely this would not imapact anything right? I’ve never noticed before but this time it is noticeable. Please see the screen shots attached and kindly advise. Activity data for 31st August screenshot taken on 1st September.

Health App data screenshot taken 1st September

Health App data screenshot taken 27th August

Note the steps are less on the most recent screen shot from 20th August to 26th August. Why is that?

Also, I have a rewards program insurance that requires a certain number of steps to receive points. This seems to have affected the pointing system for the health insurance app.