Eastern gray squirrel and Tree squirrel

Eastern gray squirrel noun - Common medium-large squirrel of eastern North America; now introduced into England.

Tree squirrel and eastern gray squirrel are semantically related. In some cases you can use "Tree squirrel" instead a noun phrase "Eastern gray squirrel".

Tree squirrel noun - Any typical arboreal squirrel.

Eastern gray squirrel and tree squirrel are semantically related. Sometimes you can replace phrase "Eastern gray squirrel" with "Tree squirrel", this phrases are similar.