I cannot claim to be an expert on bee identification, and tend to rely on their colour patterns. This one, the Garden Bumblebee, has three clear colour bands - a yellow neck, a yellow waist and a white tail. Buff-tailed and White-tailed bumblebees are very similar, but their middle band is on the top of their abdomen, rather than the midriff on the Garden Bumblebee. Garden Bumblebees also have a longer white tip.