These two species are the most widespread in the UK and frequently share the same habitat so it is these that form the bulk of the potential confusion.
They are actually quite easy to distinguish once a couple of key features are known, chiefly the so-called Coenagrion “spur” and the width of the antehumeral stripe. These are not necessarily always visible and there are a couple of other features which can help.
[If this proves difficult to read click on the image for a larger version.]
