The flute is an ancient instrument and exists in various forms in most parts of the world.
To get an idea about the flute as an instrument of the world, take a peep into the following sites.
Flutes across the globe as such are fairly similar in construction
(with the exception of the western flute) and the versatility they offer to the musician.
For example, an Indian flautist will be able to pick up an Andean flute (and vise verse)
and produce some music on the first go. This is not very different than
a guitarist picking up a Mandolin or a Ukalilli and producing some music.
On the other hand, flautists of each culture have developed their own technique
and very distinctive styles in accordance with the music of the land.
The uniqueness of the
bansuri (just like other flutes of the world)
is not so much in its construction as it is in the way the instrument is played.
Here are some web pages which talk a little bit about the bansuri.