Linux

The kernel differences
2.4 and 2.6

2.4 has .o objects for the os to come up. Which means that the user space programs are used for linking and bringing up the OS. But 2.6 uses .ko objects for the os to come up. which means that it uses kernel space programs for linking and bringing up the OS also which make the OS fast in booting.

The schedulers
2.4 uses a O1 scheduler whereas 2.6 uses a On scheduler algorithm