meaning - Ups and downs: かみ・しも vs うえ・した

So, we have the kanji 上・下 which can be read as either かみ・しも or うえ・した, and as I understand it, those two are antonym pairs. But what are the differences between the two?

The thesaurus isn't very helpful. For instance, it says, for うえ

何かとくらべて高い方の位置、場所。

and for かみ it says

位置が高いこと。また、ひと続きのものの初め。川では上流、和歌などでは前半をいう。

If I understand this correctly, this is saying that うえ is simply the place or position above some reference level, while かみ is the state of being above, or the start of a series. But the dictionary entry for かみ goes on to give definitions like

位置の高い所。

which bring it right back into the territory of うえ, or at least very close. It almost looks like the distinction is supposed to be relative vs absolute, but this just confuses me since, at least in my mind, above/below are inherently relative.

Question. What are the differences between かみ・しも and うえ・した? Are there minimal pairs illustrating these differences?

Answer

AFAIK, うえ・した is just "(on) top/above vs. (on) bottom/underneath".

かみ・しも is usually "upper vs. lower", meaning talking about different parts of the same thing. The easiest example of this to remember is "upstream" vs. "downstream" (川上【かわかみ】 vs. 川下【かわしも】) or "upwind" vs. "downwind" (風上【かざかみ】 vs. 風下【かざしも】). Also, more generically, 上手【かみて】 (upper part) and 下手【しもて】 (lower part).

Other than these few examples, the only other ways I've seen かみ・しも used are referencing place names (地名). An example in Osaka is [上新庄]{かみ・しん・じょう} and [下新庄]{しも・しん・じょう} (upper and lower Shinjou). You can see on the map that they are pretty even north-south-wise, so the 上 and 下 probably refer to their positioning along the Kanzaki river which empties into Osaka Bay to the southwest. Another is [桂]{かつら} and [上桂]{かみ・かつら} near 嵐山 in Kyoto. Also, [上京区]{かみ・ぎょう・く} and [下京区]{しも・ぎょう・く} districts in Kyoto.

TANGENTIAL NOTE: notice that 上手 and 下手 both have multiple readings that mean different things.

上手

• 上手【じょうず】（じょうず）／上手【うま】（うま）い　→　Skillful; clever; good at


• 上手【かみて】（かみて）　→　the upper part; stage left


• 上手【うわて】（うわて）　→　to be better than someone else at something; to "have the upper hand" (advantage); overhand (sumo throw / baseball pitch)

下手

• 下手【へた】（へた）　→　lack of skill; poor; bad at



• 下手【しもて】（しもて）　→　the lower part; stage right


• 下手【したて】（したて）　→　take a lower position; being humble/modest; underhand grip (sumo / baseball)