i believe it have specialty in some of side extra notes and main notes is pristine! the Kodo master i got it from have it associated with plum blossoms smell, and definitely experiencing more pieces give better judgement regarding its main and side notes in general and make its easier to narrow the differences between them, i believe that's tue for each type of wood not only Kyaras.
I'm not pretty good at explaining but I'll try my best.
i probably tested over 40 different green oil Kyaras and while they are all green oil they all differ in ways or another some were special and highly ranked some are average and below average in term of main notes and side ones.
you can see it like how people belong to same lineage or clan and you can't mistake them but there is the differences in ther voice, eyes, hair, nose, lips etc "hope this is good example" lol:/
in Japan there is a ranking system for the woods not only the Kyara the wood fall under one of the 9 ranks depends on its performance and other criteria "honestly i don't know much of it but I'll share what i found".
to note also there is always special pieces and those are mostly ranked under the top rank.
here a picture from Japanese incense book regarding the rankings.
Translation "thanks to Japanese dude in Reddit for helping me out" 🥰
上々: Excellent
匂いが上品で、炷き始めから炷き終りまで同じ匂いで同じ出方をするもの
A fragrance that is elegant, maintaining the same scent and performance from the beginning to the end of burning.
上中: Very Good
最初から匂いが強く出て、良い匂いのまま最後まで同じ程度に匂うもの。
A fragrance that starts strong and maintains a pleasant scent consistently until the end.
上下: Good
匂いは劣っても出方は初めから終りまで平均しているもの。
If the scent is not as superior, the performance remains consistent from the beginning to the end, averaging out the intensity.
中上: Above Average
いい匂いが出ても終り頃には匂いが薄らぐもの。
A fragrance that starts with a pleasant scent but fades towards the end.
中々: Average
少し強いけど、それでもいい匂いが出て、終りに薄らぐもの。
A bit strong initially, but still produces a pleasant scent that fades towards the end.
中下: Below Average
前者より少し品の落ちるもの。
A bit less refined compared to the average.
下上: Poor
匂いは柔らかく出の具合も穏やかですがすぐ消えうせるもの。
The scent is soft, and the intensity is mild, but it quickly fades away.
下中: Very Poor
下上に次ぐ匂いのものですぐ消えるもの。
A fragrance that follows the previous one and fades away quickly.
下々: Terrible
匂いも宜しくなければ出方も不規則なもの。
Fragrance is not pleasing, and the performance is also irregular.
now most of Kyaras i owned or shared with me by friends is named pieces, most of named pieces have specificity however doesn't necessarily its better than unnamed one still usually its better and it got a name for a reason.
regardless not all named pieces are special there is some kind of tradition or something else that make them name pieces of wood.
usually the kodo master do the naming of pieces after experiencing the wood he would classify the wood, rank it, its notes in general and give it waka poem and write etxra details like the date of session and other stuff, but also in japan there is many pieces were named by emperors, family heads and so on.
here example of paper written by master for certain Kyara.
i remember reading that naming wood started in japan in Heian period and its still going to today.
that tradition or whatever its made the famous incense of japan exist, named piece doesn't mean its famous but famous pieces is named piece.
like Ranjatai, or Zenasaka or 61 famous pieces
"chosen by founders of shino and oie" 120 pieces and so on.