The Lesser Redpoll was split from the Common (Mealy) Redpoll (Carduelis flammea) only in recent years. They are very similar; the Lesser is a little smaller and darker.
They are also similar to other (non-UK) Redpolls and fairly similar to the Linnet (Carduelis cannabina).
The Lesser Redpoll's range is north/central Europe, mainly British Isles and Denmark, plus introduction to southern New Zealand (unlike Common Redpoll and Linnet).
The female has a red crown but not a red breast; the male has both and the juvenile has neither and is more streaky.