What's the difference between a light noun and a nominalizer?

Question

I've been studying Japanese, and sometimes I see some words, like の and こと, get classified as "nominalizers," and other times as "light nouns." Plus, I've read somewhere that light nouns sometimes evolve into nominalizers, or something of sort. I'm kind of confused about the definition of these two things.

As far as I can gather, a nominalizer is more abstract than a light noun, which is in turn more abstract than a normal noun. But what are the criteria for a noun to be called a "light noun"? And what are the criteria for it to be called a "nominalizer" instead?

Are nominalizers and light nouns even distinct concepts? Or can a light noun be a nominalizer and vice-versa?

Edit: for example, the term "light noun" is used in the following passage:

indefinite-pronoun structures in Japanese involve a light noun at the right periphery—no ‘thing’, hito ‘person’, tokoro ‘place’, toki ‘time’, etc.

Answer 1

The terminology is most commonly used in Sino-Tibetan, Japanese and Korean contexts. I suggest taking a look at this (warning: gigantic volume, probably a good idea to find an electronic version if you have access to one):

Yap, F. H., Grunow-Hårsta, K., & Wrona, J. (Eds.). (2011). Nominalization in Asian languages: Diachronic and typological perspectives (Vol. 96). John Benjamins Publishing.

But basically, a nominaliser is something that is 'more grammaticalised' than a light noun, using the usual criteria for grammaticalisation (e.g. obligatoriness, semantic bleaching, phonological reduction, boundedness, etc.). Where we draw the cut-off line between light noun and nominaliser will depend on the author, language and descriptive tradition, and if a paper uses both terms, you should look for a definition of the two (otherwise it's not a very well written paper).

By way of example, we can use Yap, Grunow-Harsta and Wrona's example of Old Chinese zhe. (Personally I have some doubts about the description, but that doesn't hurt the overall point.) In Old Chinese, they consider zhe a light noun because it can also appear in contexts where it's clearly serving as a lexical head, being modified by a demonstrative and a numeral, and modified by a relative clause introduced by zhi:

(1) 此 五  者
    ci wu zhe
    DEM five ZHE
    'these five things'

 (2) 其   謂   霣     之   者   
     qi   wei  yun    zhi  zhe
     3    call fall  ZHI  ZHE
     'what he describes as falling'  (Lunheng)
     (Note: 霣 = modern Chinese 殞)

However, 者 already different from lexical nouns (say 物 'thing') in that it is more semantically bleached - it can refer to abstract things, points in time, objects, people, etc. - it can be modified freely even without 之 (actually examples like (2) are extremely rare in my experience), and so on. So it already has a plenty of properties that set it aside from 物.

In Middle Chinese 之 started declining in frequency and examples like (1) and (2), where it displays properties of a lexical noun, were no longer productive, leaving only uses of 者 like this:

(3) 愛   人     者
    love others ZHE
    'those who love others'

At this point it is called a nominaliser. (In Middle Chinese, we also started seeing 者 being used to connect a clause and the lexical noun it modifies, i.e. it became a relativiser as well, though this isn't so relevant to the current question.)