Cerulean Kingfisher
Alcedo coerulescens
The cerulean kingfisher is a small kingfisher with a length of 13 cm (5.1 in). The upperparts are a range of shades of blue with white lores and a prominent white patch on each side of the neck. The underparts are white with an azure-blue breast-band. The bill is blackish and the legs are dark brown. The female has duller and slightly greenish plumage and a narrower breast band.
ID text from Wikipedia, CC BY-SA 4.0

Common Kingfisher
Alcedo atthis
This species has the typical short-tailed, dumpy-bodied, large-headed, and long-billed kingfisher shape. The adult male of the western European subspecies, A. a. ispida has green-blue upperparts with pale azure-blue back and rump, a rufous patch by the bill base, and a rufous ear-patch. It has a green-blue neck stripe, white neck blaze and throat, rufous underparts, and a black bill with some red at the base. The legs and feet are bright red. It is about 16 cm (6+1⁄2 in) long with a wingspan of 25 cm (10 in), and weighs 34–46 g (1+3⁄16–1+5⁄8 oz).
ID text from Wikipedia, CC BY-SA 4.0

Where you might meet both
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Play today's Daily BirdPhotos and recordings are credited to their authors under the licence shown. Full profiles: Cerulean Kingfisher and Common Kingfisher.