How do expressions like "more than" and "is more than" have different meanings?

Question

I've looked up in my present math book that expressions like (1) "less than" and "is less than" and (2) "more than" and "is more than" have different meanings. I saw that "less than" indicates subtraction and "is less than" indicates a number that's smaller than another, likewise for "more than" and "is more than." Am I on the right track? I told you before that I got this out of the math book I have right now. Please help me on this!

Answer 1

I guess you're correct

It's like $20$ is $5$ less than $15$ and

$20$ is less than $21$