What's different between 33 with 66 (tickrate)

[wjdgns421]

I run 3 server.

zombie escape
gungame
deathrun

I set tickrate 66 ze,gg and deathrun is 100
I know If I set tickrate 100, Player is nice bunny hop better then 66.
But I don't know 33 and 66. What's difference?
I can't understand in wiki.
( sv 33per/s , 66per/s, 100per/s, blablabla)
Plz help me about understand this.

Thank you