They are pronounced similarly and are both translated into "because". What is the difference in their meaning? When should I use one over the other?
"应为" does not mean "because". If it is used as because, then it is an error, maybe a typo.
"应为" used together, it is usually two separate words, and can mean "should(应) be(为)".
We can break down the expression into individual characters:
- 「因」means reason;
- 「爲」(为), in this context, means to be.
In contrast, 「應」(应) means should.
- 「因爲」is reason + be = because
- 「應爲」can be seen as a shortening of 應該爲 (should + be)
Also, note that「因」is pronounced yīn, while「應」is pronounced yīng.
应为 for "because" is a typo. It's not in 汉语大词典，for example.