Black-thighed Puffleg
Eriocnemis derbyi
The black-thighed puffleg is about 10 cm (3.9 in) long. It has a straight blackish bill. Males are mostly shining golden green overall, sometimes with black highlights, and has glittering malachite green upper- and undertail coverts. Their leg puffs are black and the tail is forked and black. Females are similar but have white underparts with green spots, and their leg puffs are a mix of black and grayish white. The female also has a blue tinge to the forehead. Juveniles resemble females. Voice: The black-thighed puffleg's only described vocalization is "a short buzzy trill 'tzzrr', repeated at irregular intervals". It is given both from a perch and while hovering, and is very different than the sounds of other Eriocnemis pufflegs.
ID text from Wikipedia, CC BY-SA 4.0
Glowing Puffleg
Eriocnemis vestita
The glowing puffleg is 9 to 10 cm (3.5 to 3.9 in) long. Males weigh 3.3 to 7.2 g (0.12 to 0.25 oz) and females 3.6 to 5.3 g (0.13 to 0.19 oz). It has a straight blackish bill. The nominate subspecies' male has shining dark green upperparts with a golden green rump and uppertail coverts. It has a glittering purple throat patch thinly surrounded by golden green. The rest of its throat and its upper breast are shining blackish green, its belly glittering golden green, and its undertail coverts iridescent purplish blue. Its leg puffs are white. The tail is forked and dark steel blue. Voice: The glowing puffleg's only described vocalization is "a single metallic note 'tseek' or doubled 'tsi-tseek', repeated at irregular intervals". It is given both from a perch and while hovering.
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: Black-thighed Puffleg and Glowing Puffleg.