Queens are the largest but are smaller than other bumblebees.
Workers are small and some look too tiny to be bumblebees.
The males have a wide yellow collar and a yellow face.
Like most bumblebees they are not easy to photograph as they spend most of their time head down in flowers. It is easier when they are on the outside.
This is the Bumblebee Conservation Trust (BBCT) identification chart and distribution map.