"还是 háishì" and "或者 huòzhě"
Both "还是 háishì" and "或者 huòzhě" share the meaning of "or" but the two words differ in key areas and each can have several additional, different meanings.
"OR"
"还是 hái shi" is used in questions
你要喝水还是茶？
Nǐ yào hē shuǐ háishì chá?
Do you want to drink water or tea?
他是老师还是校长？
Tā shì lǎoshī háishì xiàozhǎng?
Is he a teacher or a principal?
"或者 huò zhě" is used in statements.
我要喝水或者茶。
wǒ yào hē shuǐ huòzhě chá.
I want to drink water or tea.
他是老师或者校长。
Tā shì lǎoshī huòzhě xiàozhǎng.
He is a teacher or a principal.
"还是 háishì" can have a meaning of "still, yet".
她还是会来的。
Tā háishì huì lái de.
She may come yet.
我还是把作业做完了。
wǒ háishì bǎ zuòyè zuòwánle.
I still finished my homework.
"还是 háishì" can express the better or favoured alternative.
你还是多穿点儿吧。
Nǐ háishì duō chuān diǎnr ba.
You had better wear a little more.
还是坐飞机快。
háishì zuò fēijī kuài.
Taking a plane is faster.
"或者 huòzhě" can be used as "maybe, perhaps"
或者下午会更好。
huòzhě xiàwǔ huì gèng hǎo.
Maybe afternoon will be better.
他们或者不应该说那样的话。
Tāmen huòzhě bù yīnggaī shuō nèiyàng de huà.
They perhaps shouldn't speak like that.