I’m gonna try my luck explaining the difference, but I have to say that even as a Chinese speaker, I haven’t got these down pat. Could be a testament to how much my Chinese has deteriorated, but even the dictionary says that these two are (apparently) equivalent in Chinese, just that one can be used as a noun, while the other is more common in poetry.
Anyway, so… see, the problem is that 栄 (traditional form: 榮) itself can carry the idea of honour or glory, and that’s why it’s so unclear… it’s actually associated with ideas like ‘prospering’, ‘thriving’, ‘having a reputation/status’. I mean, look at the traditional form and imagine the energy and vigour of the blazing flames. That’s what it’s like.
So how can we tell them apart? I mean, I tried using a Japanese dictionary, and when I started from the definition of 栄光, with a 1-2 clicks on words I didn’t know, I ended up on definition that used 光栄, so it’s obvious that they’re really close. What I’m going to do is to concentrate on parts of the definition where the same words were used, but in different constructions, and then try to link those words to the kanji. Here are the relevant bits (my translations may be literal at times to avoid contrived associations with ‘honour’ or ‘glory’ that don’t use the kanji for justification):
光栄: …名誉に思うこと。= an abstract thing thought of as one’s reputation/fame
栄光: …大きな名誉。= a big/great reputation/fame
So it seems that 光栄 is something that can be thought of in a manner that contributes to one’s reputation, or as something that gives one a reputation, whereas 栄光 is that reputation. Why is that? Well, generally (though not always), what comes before modifies what comes after. In other words, in the first case, 光 describes 栄, whereas in the second 栄 describes 光. In addition (though this may be more confusing that helpful), in Chinese, 光 can be a verb that means ‘to cause to shine/become brighter’ (figuratively, usually), whereas 栄 isn’t a verb at all. Thus:
- 光栄 is a bright state of thriving and prosperity, a sort of shining status or reputation. Admittedly, that sounds like both ‘honour’ and ‘glory’, but if we take the ‘光 is a verb’ interpretation, we’ll realise that something that ‘makes one’s reputation shine’ has to be an honour, whereas glory is the result of that honour. I personally tend to think of 光栄 as an adjective more than a noun, because if I say 光栄です, I’m more focused on the fact that something is ‘honourable’ than that it is, for instance, ‘the highest honour that the nation can bestow upon…’. More importantly, (and this should help clear up the confusion)…
- 栄光 is the light of fame, of a good reputation, of prosperity, of thriving. That’s what the 光 in second position indicates. That means that 栄光 is something that shines upon others and draws their attention. Only glory does that. Honour is more of an internal thing, and someone who is honoured does not necessarily ‘shine’ upon the world because he or she may not be honoured publicly. Therefore, 栄光 is glory.
That’s my analysis anyway. But how I personally remember it is: 光栄 feels like an adjective, while 栄光 feels like a noun, specifically a kind of light. After that… I work from there. What’s more like a light, and what’s more like an adjective? I mean, we don’t say ‘it’s been a glory’, do we? Only ‘it’s been an honour’.