What is the difference between $\gg$ and $\gt$ ?
Thank you $\infty$ times.
Imprecisely, we usually say that $a\gg b$ means that $a$ is much larger than $b$. Of course, this seems like it depends a great deal on how you define "much".
I usually only see this notation used in asymptotics: that is, we take $a\gg b$ to mean the same thing as $b=o(a)$, which means that $a=a(n)$ and $b=b(n)$ depend on some $n$, and $$ \lim_{n\rightarrow\infty}\frac{b(n)}{a(n)}=0. $$