Brown Tinamou
Crypturellus obsoletus
The brown tinamou is approximately 25 to 30 cm (9.8–11.8 in) in length and it weighs about 350 to 550 g (12–19 oz). Depending on the subspecies involved, the upperparts vary from dark sooty-brown to bright chestnut and the underparts, which usually are paler than the upperparts, vary from chestnut to light ochraceous. The subspecies griseiventris is unique in having pale buff-grey underparts. All subspecies can be separated from the superficially similar little tinamou by the greyish (rather than whitish) throat. Females are typically larger and more rufescent than the males.
ID text from Wikipedia, CC BY-SA 4.0

Cinereous Tinamou
Crypturellus cinereus
The cinereous tinamou is a shy and secretive bird. It is approximately 29–32 cm (11–13 in) in length, and the male bird weighs around 435 grams (15.3 oz) and the female of the species weighs 549–602 grams (19.4–21.2 oz). It is colored similar to the Berlepsch's tinamou in that it is dark brown to sooty brown or brownish black in coloration. It tends to be slightly more brown than the Berlepsch's tinamou. It is recognized by its smoky-grey with reddish-brown crown and nape. The feather shafts on side of its head are white, which shows through on occasion.
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: Brown Tinamou and Cinereous Tinamou.