Great Spots are found widely throughout Britain, they are common in woodland and readily visit garden feeders. Lesser Spots are scarce and rarely seen. So you are much more likely to see a Great Spot than a Lesser Spot.
You can easily tell the difference………..
Great Spots are quite large the size of a Starling or Blackbird.
They have a crimson patch under the tail, a clearly defined black and white back and spotted wings.
Males have a red patch on the back of the head, females do not.
Lesser Spots are tiny, the size of a Sparrow or Chaffinch.
There is no red under the tail and the back and wings have black and white bars/stripes.
Males have red on the top of the head, females do not.
For more detailed information on how to tell them apart watch BTO woodpecker identification video