Two small, brown birds. Both come to Britain in the summer months in fairly large numbers in order to breed. They like spending their time in reed beds or thick undergrowth and they both have pretty similar songs.
Below is a short video of the two birds in question, hopefully showing the difference in the two songs. The first bird is the Reed Warbler, a song which is 'chatty' and slow paced, consisting mostly of jittery notes which are repeated 2-3 times, interrupted by occasional mimicry or whistles. The second is the Sedge Warbler with a Reed Warbler in the background, this song is a series of long, loud sequences of not very varied excited notes relieved by rapid cascades of trills and whistles and occasional mimicry.