recommend som tools in Ubuntu

[loody]

Dear all:
Would you please recommend some tools that can be use under Ubuntu?
1. binary files compare.
    diff only will show the result of comparison of 2 binary files. Is
there any tool can tell me where the differences are and show them in
2 columns line winmerge?

2. what kind of muti-login demon that Ubuntu used?
    in Ubuntu system, we can login in different console by Fn+1,2,3.....
    Can we have the same feature on embedded system? If we can, what
tool is most used for multi-login on embedded system?
appreciate your help,
miloody