I'm in the Xbox One Preview Beta Build but yet I'm not getting the new Beta Build features.

My light is still white (7am UK time). I'm in the preview but should still get the update to move me up to the final build from beta stage.

Ah, in that case, anyone in the beta experiencing this issue should post over on the March Preview Update forums - the engineers keep a close eye on those forums for any new issues with the preview builds, and it's a quicker way to get beta-related issues
seen by Xbox Staff.

Are either of you in the Minecraft Preview program? If you are on a preview/beta build that he is not, that can be one reason.

The Beta build may have some features "in test" that the standard build don't have, sometimes new UI and so on... as the name says, is a beta that you can use to test and they get feedback about it.

If you want a detailed list of difference, you can simply install the beta, read the description on Microsoft Store, and test it out by yourself.

This is the game's developer notes as released on 28 November 2018

PLEASE READ before participating in the Minecraft Beta - 1.9.0.2 :

You will not have access to Realms and will not be able to join non-beta players while you're previewing the beta. Featured servers may also be unavailable

The beta is available only on Xbox One, Windows 10, and Android (Google Play). To join or leave the beta, see aka.ms/JoinMCBeta for detailed instructions

Beta builds will likely be unstable and are not representative of final version quality. Please backup your Worlds before joining the beta

Finished releases may not include all new features, changes, and fixes from the beta to preserve stability and may slip to a later release