Difference between 〜に限らない and 〜に限られていない?


I'm a bit puzzled by the use of 〜に限らない vs 〜に限られていない. Here are example
sentences from a textbook:

>   1. 日本語を勉強している学生は、日本語専攻に **限りません** 。
>
>   2. 最近、プロの相撲の力士は日本人に **限られていない** 。
>
>

These both mean "not limited to", and have the same sentence structure. Here
are my specific questions:

  1. How is 限られていない being used as a passive verb here?
  2. Would 限られない work?
  3. Does sentence (1) have the same meaning as:

> 日本語を勉強している学生は、日本語専攻に **限られていない** 。




  1. 限られていない is the te-form of the passive voice of 限る, followed by いる to denote the continuation of state. So the literal translation is "has not been limited". Basically ～ていない focuses more on how things have been up until now rather than how things are now, but in this case the difference is not very important.
  2. Of course it works. 限られない is the plain passive form of 限る, "is not limited".
  3. Yes. 限らない and 限られない have the same meaning because it works [both as a transitive and intransitive verb](http://jisho.org/word/%E9%99%90%E3%82%8B). I think 限らない is more common and concise, though.

All in all, 限らない, 限りません, 限られない, 限られません, 限られていない and 限られていません can roughly mean
the same thing.




  1. 限られていない is the te-form of the passive voice of 限る, followed by いる to denote the continuation of state. So the literal translation is "has not been limited". Basically ～ていない focuses more on how things have been up until now rather than how things are now, but in this case the difference is not very important.
  2. Of course it works. 限られない is the plain passive form of 限る, "is not limited".
  3. Yes. 限らない and 限られない have the same meaning because it works [both as a transitive and intransitive verb](http://jisho.org/word/%E9%99%90%E3%82%8B). I think 限らない is more common and concise, though.

All in all, 限らない, 限りません, 限られない, 限られません, 限られていない and 限られていません can roughly mean
the same thing.

