what is the difference between zimage bz image and u image

the difference between bz image and z image is in compression mode
not only compression mode
there are many differnces

A uImage file is a kernel with a modified header for u-boot. A tool called mkimage is used to convert a zImage (regular kernel compressed image) to a uImage file. And No, zImage files, as they are, are not compatible with U-Boot. You must convert them

make zImage - Creates a gzip’d kernel image that must be installed manually.
make bzImage - Creates a bzip2’d kernel image that must be installed manual

bz image is compressed image when compared to  zimage

suggest me if any thing wrong

what is the difference between zimage bz image and u image