Why is my husband able to complete his circles and burn more calories with less movement then me?

Different people have different bodies. Some people can burn calories easier than others for a variety of reasons such as age, size, gender, height, etc. It's just the way the body works. The Apple Watch uses these factors when calculating the progress of activity circles. You can see more about that here: https://support.apple.com/en-us/HT204516. The Apple Watch also isn't a perfect measuring device and there is bound to be a margin of error between multiple devices, which is also something to consider.

It's based on the person information you put in. Unless you put exactly the same weight, height, age and gender in as your husband, things are going to be different. If you happen to be female, your metabolism is going to be quite different from your husband's. If you're male, the difference can be based on height, age or weight.