Reading the Wikipedia pages on “Ghee,” “Clarified butter” and “Beurre noisette” has left me somewhat confused as to what ghee is. Some statements on the pages seem to suggest that it's always clarified butter, some that it's always beurre noisette, others that it can be either of the two depending on regional variations, and then it also might just be something in-between. Can someone clear up my confusion? Does it make (much) of a difference for cooking Indian recipes (I presume not, as ghee plays a less prominent role in a curry than beurre noisette does when it's used as a sauce).
Judging from those Wikipedia articles:
Clarified butter is rendered butter, which means that the solids are removed. Beurre noisette is browned butter, which contains the solids.
Ghee is slightly-browned (it should have a golden color) butter that is rendered. So you melt the butter till it's golden. Then you remove the solids by pouring the top layer into a container. So you have a combination (if you like) of clarified and browned butter.
I was doing some product demonstrations at an Asian market in Portland once, and an Indian vendor treated me to some of his samples brushed with a brownish ghee. I mentioned that I had never seen this kind of ghee before; I was used to a more yellowish, clarified-butter style.
He told me "Yeah, my wife hates it when I make this kind of ghee, but I prefer it because it has more flavor."
So, there's at least some anecdotal evidence that within the Indian ghee can vary in style from a simple clarified butter to a strained brown butter. His was slightly less brown than when I make a brown butter, but I suspect there's a broad continuum.
The primary distinction between ghee and beurre noisette is twofold:
In preparing ghee, every effort is made to ensure that all of the water is evaporated from the butter, so that it is has good long term storage properties. Evaporating the water is a side effect in making beurre noisette, and so it may or may not be fully purged, and room temperature storage is not recommended.
In preparing ghee, the milk solids are left behind (again, so that it has a long shelf life), and the product is essentially pure milkfat.
Any color imparted to ghee during the preparation is flavor and color compounds that have dissolved into the fat phase, as the milk solids are not part of the final product.
In beurre noisette, the browned milk solids and the flavor that they impart are the entire reason for making it, so they are included in the final product. The name reflects the color (as of hazelnuts) of the browned butter, due to the browning of the milk solids.
For your question if ghee is clarified butter or not, the answer is yes, it is sort of clarified butter but it is not Beurre noisette. As for your confusion, it is not Beurre noisette as for beurre noisette you need to caramelize the milk solids present in the butter to achieve the nutty flavour profile and a little bit browning of the product.
It does not make much difference if you use either of ghee or beurre noisette to cook Indian recipes because there are many Indian recipes that are changing across the globe according to people's taste preferences.
Both have a nutty flavour but beurre noisette still contains the milk solids. Ghee doesn't (unless the person using the word "ghee" is for is unaware of the differences so not using its technical meaning).
Beurre noisette (also known as brown butter, sometimes 'caramelised butter') is whole butter. It shouldn't have water content but can sometimes still have some water remaining. Ghee is a toasted form of clarified butter (milk solids removed), and never has any water content. It keeps better than whole butter and has a higher smoke point.
Beurre noisette - butter is heated until the milk solids in it are toasted. All the water content is usually cooked off during the browning process. (In black butter the heating just continues to a darker colour.)
Clarified butter is any butter where the milk solids (protein) have been removed. - because there are no milk solids it burns less easily (at a higher temperature). It keeps better than whole butter and has lower (or no) water content.
For the specific kind of clarified butter called ghee (an word from India where the form originated), the butter is heated, the milk solids sink, then heating continues until the milk solids are toasted. The milk solids are then separated (and used in other recipes or discarded). The process gives ghee, unlike the european forms of clarified butter, a nutty taste and a browned colour (depth of colour to taste). The cooking process required also removes all the water content.
Regular (or classical European) clarified butter is heated to a low simmer so the milk solids float to the surface where they are skimmed off off before they change colour. It has no toasted flavours and, given the shorter process needed, usually has a significant proportion of the water still in it.
Ghee is clarified & browned (fait noisette) butter (beurre).
Of course, the degree to which it's browned can vary to taste or custom, as I'm sure it does with beurre noisette too.
Note also that, if you intend to produce ghee, you need to brown before clarifying; it's the milk solids that will brown, and clarifying removes them leaving only (in the case of ghee, infused) butterfat.
The only difference between buerre niosette, brown butter, and clarified butter is the milk solids are cooked longer... with clarified butter you stop the process before the milk solids get toasted (and sometimes remove the solids), brown butter they are toasted and black butter they are basically burnt. that's where the name comes from. Ghee is clarified butter traditionally boiled to clarify making it not brown or black... but technically all of them are ghee.