Fraxinus micrantha

Fraxinus micrantha Lingelsh., Bot. Jahrb. Syst. 40: 217 1907.; 

Nepal; Pakistan; West Himalaya as per Catalogue of Life;

Common name: Small-Flowered Himalayan Ash
Having little knowledge about tropical and subtropical trees (except some growing in Delhi), I tend to mix them. This was the tree growing along Nainital lake and known as Bangar (as a local told me). The other tree identified by ... as Lannea coromedelica grows common along hillsides.
Could this be what ... suggested as Boswellia serrata, a very wild guess though. Perhaps two forms are growing side by side, one with perfectly green leaves and one having leaves with reddish tinge.
The tree looks quite like Boswellia serrata as you mentioned.
I think this is not Boswellia serrata. It somewhat resembles Lannea coromandelica.
I thought they look different, especially the hanging inflorescence along with leaves. Let us see other views. I am novice regarding trees.
The plant is not Lannea coromandelica. L.c. is a very common avenue tree in Chennai. I have beautiful photographs of this plant. I will post them after searching from my old files.
I am also of the opinion that it is something else.
This tree is Fraxinus micrantha common in Nainital. The local name is Angu. In English, it is called Ash.