what's the difference of 变成 and 变为?

The difference between 变成 (biànchéng) and 变为 (biànwéi) is subtle but important. Here’s a clear breakdown:

Although both 变成 (biànchéng) and 变为 (biànwéng) convey the meaning of “changing into something” or “becoming,” they are distinguished primarily by formality and contextual usage.

Core Similarity

Both 变成 and 变为 are verb-complement structures:

• 变 (biàn) = to change
• 成 (chéng) / 为 (wéi) = into, to become (acting as resultative complements)

They both mean "to change into," "to turn into," or "to become" something else, and must be followed by a noun or noun phrase as their object (the result).

Example from Common Chinese Synonyms Discriminated.pdf:

• 十年来他从一个普通员工变成了一个大公司经理。
• 我们应该由被动变为主动。

Key Differences

Detailed Explanation with Examples

1. 变成 (biànchéng) - The Default, All-Purpose Choice
This is your go-to word for most situations. It focuses on the end state.

• Document Reference: Modern Mandarin Chinese Grammar lists it as a key verb meaning "turn into (something)."
• Examples:
  • 这里原来是一个小镇，现在变成大城市了。 (From Using Chinese Synonyms.pdf)
  • 几年之后，他已经变成一个大人了。 (同上)
  • 你觉得坏人能变成好人吗？ (From Modern Mandarin Chinese Grammar.pdf)

2. 变为 (biànwéi) - The More Formal/Literary Choice
It is equally correct but sounds more formal. Its signature usage is the 变X为Y structure, which is very concise and powerful.

• Document Reference: Common Chinese Synonyms Discriminated.pdf explicitly states: "变为 can also take the form of 变X为Y, as in 变废为宝 (to turn wastes into treasures)."
• Examples:
  • 变废为宝 (biàn fèi wéi bǎo): To turn waste into treasure. (A classic idiom)
  • 化悲痛为力量 (huà bēitòng wéi lìliang): To turn grief into strength. (Note the use of 化...为, a parallel structure).
  • 我们应该由被动变为主动。 (From Common Chinese Synonyms Discriminated.pdf)

Practical Summary & Advice

• In daily spoken Mandarin and most writing, use 变成. It is perfectly natural and accurate. If in doubt, choose this.
• Use 变为 when:
  1. You want a more formal or literary tone.
  2. You are using or echoing the 变X为Y structure for rhetorical effect (e.g., in a speech, essay, or report title).
• They are largely interchangeable in meaning, but the choice affects the style of your sentence.

Think of it like this:

• 变成 is like saying "turn into" or "become."
• 变为 is closer to "transform into" or "be converted to," and is the structure used for classic proverbs like "turn weakness into strength" (变弱为强).

Therefore, while both indicate a change of state into a new result, 变为 carries a more formal, deliberate, and sometimes transformative connotation, especially in its fixed patterns.