just want to know when using a xboot to boot an iso image if there is a kernel in Xboot utility or it is only a bootloader, that's all!!
I will try again, what you asked (and as well the above quoted sentence) makes not any sense.
Xboot is a tool (coded in .Net 4.0 ) to attempt to make things easier to make a multi-boot setup on a USB stick.
It is nothing but a "wizard" or "helper" to ease the use of tools like Syslinux/Isolinux/Memdisk and/or grub4dos (which are BOTH and AT THE SAME TIME bootmanagers AND bootloaders - for some Operating systems only - AND in the case of grub.exe ALSO a DOS executable AND a Linux kernel).
You started a thread in "Boot Linux and other OS flavours", while there is a dedicated forum for Xboot:
There is a sticky there "Introduction to XBoot.":
which should have made that clear.
If you detail the actual problem you have been experiencing, then - hopefully - someone may be able to help you with it , but right now I have no idea of what the actual problem is .