someone else是其他人.
eg:we agree with you,but someone else don't agree with you.
我们是相信你,但是其他人并不相信你.
another one是另一个人/再来一个
eg:You choose me,then he will choose another one.
你选择了我,那么他就会选择另一个人了.
we have finish this cup,please give me another one.
我们已经喝完了这杯,请再来一杯.