a person or thing that is not near the speaker or as near to the speaker as another =

a person or thing that is not near the speaker or (that is) as near to the speaker as another (is).

1.划线部分为定语从句，由 or 连接说明与前面的定语从句并列。

2.这个定语从句本身，是一个含有比较状语的复合句。补充完整后即很清晰。