While creating a wardrobe(dressing?) in a new room , we wonder wich speaker is most suitable. The room mesures 3 m x 2,5m 

these two speakers are totally different:

Beolab4 is an active speaker and can be driven by any B&O system.
Beovox1 is a passive speaker and needs to be fed by an amplifier.

If you really need/ want music in your dressing, I think both of them would do a good job, but the Beovox has the advantage that it can be built into the wall.