Is Nuclear Spin Isomer a kind of allotrope? In my book there's a question:


  Does $\ce{H2}$ shows allotropy ? Enlist its allotropes and their application?


I pondered  over different way Hydrogen can be arranged(I don't know but I have weak intuition that hydrogen bonding can play a role) but to no resolute

After awhile I googled to find different answers :Some are enlisting NSIs of hydrogen as allotrope

So can NSI(s) of an element can be considered allotrope ?

If yes then how Nuclear Spin Isomer  can affect their physical form/structures?

*Wikipedia also doesn't enlist any allotrope of $\ce{H2}$ as such.
https://en.wikipedia.org/wiki/Allotropy
Some peer review journal articles and an India high school textbook and various study guides do refer to the spin isomers as allotropes.  

There are physical differences such as different heat capacities.  See Orthohydrogen, Parahydrogen and Heavy Hydrogen for comprehensive information.  

However, aside from the spin isomers, there are genuine allotropes of hydrogen.  Solid hydrogen has two normal pressure allotropes, a face centered cubic and a hexagonal closest packed allotrope.  

Also, at high pressure, there is metallic hydrogen.