- Mainland uses simplified characters; Taiwan uses traditional characters
- Mainland uses Hanyu Pinyin, a Chinese Romanization scheme, as the standard for teaching Chinese and denoting pronunciation in dictionaries; Taiwan uses Bopomofo (ㄅㄆㄇㄈ)
- For metric length units, Mainland uses "米, 釐米, 毫米"; Taiwan uses "公尺, 公分, 公釐"
- Mainland uses Gregorian calendar; Taiwan uses the Minguo calendar (although Gregorian is becoming ever more common)
- For Western movie names, Mainland often translates literally; Taiwan often adds its own interpretation, e.g. Pirates of the Caribbean: The Curse of the Black Pearl is known as "加勒比海盜：黑珍珠號的詛咒" in Mainland; and "神鬼奇航：鬼盜船魔咒" in Taiwan, I, Robot is known as "我，機械人"; and "機械公敵" in Taiwan
- For technology terms, Mainland also translates verbatim; while Taiwan usually uses words that are more literary, e.g. "computer" is translated as "計算機" in Mainland; and "電腦" in Taiwan (although many Mainlander are used to "電腦" too), "mobile phone" is translated as "移動電話" in Mainland; and "行動電話" in Taiwan
- The quotation mark is different too. Mainland uses “”; Taiwan uses「」 (Most people probably don't notice this)
Upon reading the first bullet point, old-guard Kuomintang would immediately raise the banner of "The communist is the destroyer of traditional Chinese culture" and use the same rhetoric to explain the rest of the bullet points. But do you really think that Mao Zedong, Zhou Enlai, and their fellows thought "we are the bad guys, so we must destroy traditional Chinese culture. To destroy traditional Chinese culture, we must do this, this, and that". Of course not. To find the root causes of these differences, one must start from the different ideologies of the two sides.
During the martial law period, the Republic of China reiterated itself as "the Chinese people", "the legitimate representation of the Chinese culture", and "the guardian of traditional values". Such ideology culminated during the Chinese Cultural Renaissance, started in 1966 in response to Cultural Revolution in the People's Republic. Because of this, Taiwan continued to use traditional characters and Bopomofo, created in the early years of the Republic. Taiwan uses "公尺, 公寸, 公分, 公釐" for metric length units because "尺, 寸, 分, 釐" were length units used in ancient China. The Minguo calendar is system similar to calendar era used in imperial age. And literary words are usually used to translate foreign terms.
On the other side, the People's Republic of China emphasized itself as the "New China", where new systems must be established, and remnants from the imperial age must be removed. In addition, Marxism downplays the distinction between races, and ultimately seeks to establish a world without racial boundaries and political borders. Under these principles, Mainland uses simplified Chinese and Hanyu Pinyin because they are "new". Mainland uses Gregorian calendar so that they have the same standard as (most of) the rest of the world, therefore removing the distinction between countries, and also moving away from a construct inherited from the imperial age. Using “” as the quotation marks is the same thing. As for metric length units in Mainland, the word "meter" was first translated phonetically as "米", then prefixed with words that represent 1/10, 1/100, 1/1000, namely "分, 釐, 毫", to construct "米, 釐米, 毫米". Such construction follows the same pattern as the origin of the metric system because "centi" means 1/100 and "milli" means 1/1000. By doing so, they adhere to the principle that the world is one big family and racial distinction should be deemphasized in Marxism.
If we only look at the intents of the two ideologies, both seem positive. So some people might say it is natural to have regional variants of the same language. No variant is better than others. However, there are still a lot of people looking at this subject with "good v.s. bad" in mind. So I feel that I must present my take on this. If we really have to evaluate the differences on a scale of "good or bad", how should we do it?
To criticize something, one must fully understand it first. One must not accept or reject something wholesale because of ideology. Every item must be evaluated separately, with science and logic. I personally think that Bopomofo is more suitable as a tool for teaching Chinese as the first language, while Hanyu Pinyin is more suitable for transliterating Chinese words with Roman letters (e.g. names on passport, or to export concepts of Chinese origin, such as Bagua). The detail reasoning of that probably warrants another full length article (Chinese only). I also think that Mainland's translation of the word "Islam", "伊斯蘭教", is better than the Taiwanese version, "回教" (the religion of Hui) because the Hui people are just a small part of the Muslims. The Gregorian calendar is better than the Minguo calendar. Imagine every country and regime has its own calendar system, isn't that very inconvenient and quite pointless. There's a reason someone invented the metric system. As for movie titles, I personally can't stand the Taiwanese practice of adding their own interpretation. How is "I, Robot" related to "公敵" (enemy of the state) in any way? Translations that are too literal or too colloquial are probably unsuitable for a cultural products in the Chinese world either. Slight modification is acceptable. For example, "Speed" (1994) is translated as "生死時速" (lit. per hour speed of life and death) in Mainland. At least the notion of "speed" is preserved. There is no way to rationalize the Taiwanese counterpart: "捍衛戰警" (lit. defending police). Last but not least, for computer and mobile phone, I think the Taiwanese version, "電腦" and "行動電話" are better because "計算機" can be confused with arithmetic-only calculator. Although "移動" and "行動" both mean "mobile", "移動" sounds more like a verb, while "行動" sounds more like an adjective. So "行動" is better.
Therefore, one must first fully understand the root cause, examine each item individually, and not have ideological prejudice.