I'm pretty sure these two coins are from the same emperor, dating from 1736-1795. However, one looks crude like most cash coins. One looks like it was made on a machine much more recently. I've seen this sort of thing a few times with cash coins. I know there were different mints and these were made over a period of years, but I don't know if that explains the difference. Why the big difference in quality? Is one a modern reproduction? But why bother?
Well, some later cash coins were minted, and both types exist. But not Qianlong (乾隆) I think. That would be too old. Bottom one is a replica. Maybe the replicas are used for decoration or in Feng Shui? Not sure. Almost all the minted ones I see are Guangxu (光緒). There are also minted Xuantong (宣統) but he didn't rule for very long. Cast coins continued up to the early Republic. (Below: ROC 1912 10 Mon)
I think mostly wear, with of course different mother coins. Edit: Just saw crossed posts. I would defer to @The Eidolon if he calls the second a counterfeit. Cast coins can be made of exquisite quality, like the one below. Calligraphic differences, quality of casting, etc is akin to ancient coins "style". The reason you think most cast coins look horrible is most are lesser style and worn that you find on the market. Its a lot like Byzantine coins, most come horrible but that does not mean beautiful ones do not exist. Machine struck ones look very different. They are only made in the late 19th century and 20th century.
Yeah, the bottom one in the OP is a modern copy. The giveaway is the weird stippling in the blank areas of field (this looks different from normal surfaces on authentic cast coins). I've seen similar for other Qing emperors, I think these are originally sold for use in feng shui but often "escape" to the wild. As @The Eidolon said, struck Chinese cash began in the reign of Guangxu (Guangdong mint is most common) but cast cash continued in parallel until a bit into the Republic (several Republic varieties, of varying rarity).
Thanks for the input. I'm surprised but also not surprised that the second one is a reproduction. As a side note, what is a good source for the most commonly accepted name for each emperor? The site I use to ID the coins, found here, is great for ID but seems to use a naming system that no one else uses, so it's not that helpful.
It's a bit complicated, but this Wikipedia page gives a good start for the Qing names. The Era name is what you would generally want on coins, not the Emperor's personal name or the posthumous name. For example, the last Emperor was named Puyi, but his era name was Xuantong. Japan has something very similar. For example, Emperor Hirohito has the era name "Showa" (昭和). Sometimes the Emperor could declare a new era to commemorate an important event or to try and get away from an unlucky one. For example, Emperor Genmei of Japan reigned from 704-717, and had 3 different era names in that short time. One of them was named Wado (和銅) = "Japanese copper" to celebrate the discovery of indigenous Japanese copper sources. (Sorry, I know this has wandered a bit off-topic. I was a Japanese major as well as an engineer long ago!) Anyway, as for the spelling, there are two mayor systems for representing Chinese in Western alphabets. The dominant one now is Pinyin, which uses mostly a one-for-one representation for sounds, but "borrows" some letters for sounds completely different from their sounds in English. So Q = ch sound, X = sh sound, C = ts sound etc. An older but still valid system is called Wade-Giles. It was commonly used by Western scholars before the Communist Era, but a few people still prefer it. It's easy to spot because it uses apostrophes to distinguish voiced and unvoiced consonants. Here's a page which shows the conversions for the Ming Emperors. 天啟 = Tianqi = T'ien-ch'i, for example. And here's a general-purpose list showing how to convert letter clusters between the two systems. For people who grew up in Taiwan, there's a separate system used to spell out characters. It's a phonetic alphabet similar to Hiragana in Japanese which can be written above or instead of characters to show the pronunciations. It's commonly called "bopomofo" or Zhuyin. People who grew up with that system often have trouble with typing characters on a Western keyboard in Pinyin. My wife, who is a native speaker, still needs help from me or the kids to spell characters in Pinyin sometimes because she's not used to it. There's also the complicated issue of traditional vs. simplified characters...
Nice explanation by @The Eidolon above of Pinyin versus Wade-Giles, and era titles versus names. Personally I strongly prefer Pinyin and avoid using Wade-Giles if at all possible. A Chinese-born friend once explained to me that she liked Pinyin because it gives the chance to use lots of Xs and Qs, and that's as good a reason as any.
