Correct me if im wrong but im pretty sure its like this: 还是is used when you want to say a question like 你要喝水还是可口可乐？ 或者 is used when just saying a statement like 我想去上海或者北京旅行。

They can choose relationship. "或者" general use in a statement, "还是" often use in question. 或者 基本解释: [maybe;perhaps] 1 [or] : in choices, or process 2 [either...or] Linking words, phrases, or clauses, says from two or more things to choose a, or two or more things Example:这个任务你可以交给Lily或者Lucy. 还是 基本解释: 1. says behavior, and remain unchanged, or not mentioned by the situation changes 2. [nevertheless;still]∶Despite the former things or before, still should consider 3. [all the same]∶Still, likewise 4. [had better]:Proposal "Whether like this" 5. [or]∶In the selection of things, or process 6. [withal]∶On the other hand Example: 1.今天我们还是学习. 2.很久不见,你还是很漂亮. 3.你还是带上书为好. 4.你去,还是他去? 5.虽然我中文不好,但我还是很想学习它.

according what i knew 或者 and 还是 has a same meaning as "or", when u want to combine 2 sentence u can use one of it. but what make 还是 different is when u want to combine more than 2 sentence. for ex : 你要学英文 "或者" 中文 "还是" 其它的？ "还是" has another meaning as "still ; had better".

“還是”usually use for a question,let somebody choose something,just like jonas said.你要喝水还是可口可乐？ and it also use when you compare one with another and give you idea you are very sure.like 还是喝水吧 or 水还是比可口可乐好. 或者 usually use for state something like jonas said 我想去上海或者北京旅行。 and it also use when you compare one with another and give your idea you are not sure like 北京或者会更好

或者is often used in Declarative sentences which means you choose one from some things. if 还是 is used in Interrogative sentences , it is like 或者 while if it is used in Declarative sentences ,it means you hope to do sth. . 天气凉了，还是多穿点儿衣服吧。 你选择他还是我？=你只能选择他或者是我。 加油！(*^__^*) 嘻嘻……