want to know the difference between different linux operation modes
 

Could someone please list the differences in the following 3 modes of Linux OS operation.
1. Native mode
2. Legacy mode
3. Compatibility mode.

If i'm not wrong, Native mode is one, where we run our 32-bit application in 32-bit OS (native). Compatability mode is where we run our 32-bit application in 64-bit OS (in compatibility mode). Could someone tell me if my understanding is right. Then, what is the "Legacy mode" is all about?

Sounds very much like homework.

I don't know what any of these mean---more important (for me): I don't know why I would care.

Here is a hint:
http://www.google.com/search?q=linux...L_enUS177US235
(Google is your friend)

I have never heard these terms as well. Where did you hear them? You can use different scheduler options. One might be better for a desktop and another would be better for a router or server.