What is the difference between LEQ and SEL?

Can you please elaborate on the distinction between LEQ and SEL? I understand they are both acronyms related to some form of evaluation or assessment, but I'm unsure of their specific meanings and how they differ from each other. Could you provide a concise explanation of what each term stands for, their respective purposes, and how they are utilized in different contexts? This would greatly aid in my comprehension of the subject matter.