The Samsung HW S801D, HW S801B and HW S811B soundbars differ mainly in colour and region of availability, although their technical specifications are very similar. Here's an overview of the main differences:

1. **Samsung HW-S801B: This model is often black. This is one of the standard versions for the consumer market.

2. **Samsung HW-S801D**: This model is often beige or cream. It is designed to blend in with lighter-coloured interiors. Technically, it is almost identical to the HW-S801B, the difference being mainly in its appearance.

3. **Samsung HW-S811B** : This model is also very similar in functionality to the HW-S801B and HW-S801D, but may have minimal adjustments in design or slight changes in specification to meet specific requirements of certain markets or regions.

In summary, the differences between these models are mainly aesthetic (colours) and may also correspond to variants for specific markets. Sound characteristics and functionality are generally identical or very similar.