Can i play a LAN Game with....

[aronnov]

bug and bull... if my friend only has bug? will there be an conflictions that will cause us not to connect or load?

 

[ruff_hi]

As I understand it, the answers are:

Can i play a LAN Game with bug and bull

Typically, yes, providing that they are run as MODs and that they are exactly the same.

... if my friend only has bug?

In this situation - NO. The mods won't be the same.

will there be an conflictions that will cause us not to connect or load?

Yes - Civ4 will not let you play together.