|Burnt Sienna, Daniel Smith watercolour.|
It varies considerably form one manufacturer to another. The Art Spectrum Natural Burnt Sienna is slightly more red and very granular - really wonderful for achieving a very granulated appearance. Schmincke make a browner version. Some manufacturers make it using mixes with Indian Red, PR101, an opaque red brown which is not the same thing at all, and really should be labelled as a hue. You have to read the label carefully so you get the characteristics you are expecting. I like this Daniel Smith version as it is a lovely neutral relatively transparent orange brown.
It is fantastic in mixes, and would be my number 4 colour in a limited palette. With Ultramarine it makes an amazing array of gorgeous greys, indigo, browns and deep blues. I'll post a chart of that combination later. You can also find it on my website.