Jerdon's Nightjar
Caprimulgus atripennis
Like other nightjars, it has a wide gape, long wings, soft downy plumage and nocturnal habits. At 26 cm in overall length, it is almost a head's length larger than the Indian nightjar (C. asiaticus), and differs from that species in its barred tail, rufous rear neck, and wing bars. The vermiculations on the crown are fine giving it a nearly uniform shade. The collar is blackish. The male has a white patch on each wing. Otherwise, their cryptic plumage is mainly variegated buff and brown, as typical for the dark tropical woodland nightjars.
ID text from Wikipedia, CC BY-SA 4.0

Jungle Nightjar
Caprimulgus indicus
The jungle nightjar is about 21–24 cm long with the Sri Lankan population (ssp. kelaarti) being smaller. Mostly grey with black streaks on the crown, it lacks a conspicuous wing patch which is rufous. The tail is greyish with well separated narrow black bars. The male has a white throat patch that is broken at the middle. The female has a rufous throat patch and submoustachial streaks. The usual call is a series of thacoo or chuck notes (at the rate of 5 every 2 seconds) like a distant engine. The song is a slow and regular, series of FWik-m notes, repeated for as long as 10 seconds.
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: Jerdon's Nightjar and Jungle Nightjar.