Eastern Red-rumped Swallow
Cecropis daurica
The eastern red-rumped swallow is 19 cm long with a deeply forked tail. It has blue upperparts other than a reddish collar (sometimes absent) and streaked chestnut rump. The face and underparts are white with heavy dark streaking. The wings are brown. The sexes are alike but juveniles are duller and browner, with a paler rump and shorter outer tail feathers. The population in mainland India, C. d. erythropygia, has the rump patch uniform dark chestnut without any dark shaft-streaks. The tail fork is shallow and the white patch on the inner web of the outer-tail feathers is indistinct. C. d.
ID text from Wikipedia, CC BY-SA 4.0

Red-breasted Swallow
Cecropis semirufa
The red-breasted swallow is similar to the mosque swallow but is slightly smaller and has longer tail streamers, both species having a blue crown and mantle contrasting with a rufous rump and underparts, In the red-breasted swallow the dark crown extends below the eye and there is no white on the underwing. The juvenile is similar to the red-rumped swallow but has blue on the side of the head rather than dull red.
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: Eastern Red-rumped Swallow and Red-breasted Swallow.