What would you call this bird?
Or either of these next 2?
The Rufous-tailed has much more intense rufous than the browner Snowy-bellied. This next Rufous-tailed shows some extra terminal dark with the tail spread that the Snowy-bellied's don't have.
So how to separate them? The bill is helpful. If you look carefully, the Snowy-bellied's looks a little shorter and straighter. It's also blacker. Rufous-tailed at most angles shows a quite pink bill; Snowy-bellied has limited pink to the lower mandible. First Rufous-tailed...
As mentioned earlier, Snowy-bellied has some pink to the underside of the bill, but any view of the underside of the bill reveals the brilliant white belly.
One last look at Snowy-bellied in reasonable light.
The first take-home is to be aware that these two birds at many angles look quite similar. The 2nd is to study Rufous-tailed closely; it's way too easy to not look carefully at this common species in the excitement of looking for new birds in the tropics.