So Skill Break is when you are making your ninjas skills better such as 4th raikages leech. But trials are something that make you able to change the skill to something else or make it better. They are similar but with skill trial you are able to change the skill itself from time to time, take Sasuke for example instead of his fire blast chase that is low float to repulse you can change it to the 20 hit combo so it would be easier to get the 30 off