Vampires have the ability to transform into alternative forms - a huge wolf, a cloud of bats, or a floating mist. You cannot switch directly between these forms without passing through human form, unless you have 10 or more ranks in the Shapechanging power.
Each of your three forms has its own equipment and inventory set. This is in fact a benefit, since each form has different equipment restrictions: as a wolf you can only wear collars, as a mist you can only wear items crafted from shadowcloth or shadowsteel, and as a cloud of bats you cannot wear anything at all. If you transform into a giant bat (via the Chiroptera Blood Rune), you will be able to wear a collar and wing spikes, but will share your equipment and inventory set with that of your wolf form.
The most convenient way to move equipment between your forms is to use a store on your home plane (see ‘help store’).
To see which wear locations your current form has, type ‘equipment slots’.