Do all armies have the same rank structure?

Basically yes.

(>>> Staff Sergeant (platoon leader or company quartermaster)

##### Army General (theatre leader)

# General Major (brigade leader)

((>>> Company Sergeant (company quartermaster)

XX Lieutenant Colonel (battalion leader or regiment vice leader)

## General Lieutenant (division leader)

### General (corps leader)

####### Generalissimus (overall supreme commander)

xx Lieutenant (platoon leader or company vice leader)

>> Corporal (squad leader)

>>> Sergeant (platoon vice leader)

> Lance Corporal (squad vice leader)

x Junior Lieutenant (platoon leader)

X Major (battalion leader)

XXX Colonel (regiment leader

###### Field Marshal (commander of the military branch)

Private (does all the menial work)

xxx Captain (company leader)

#### Colonel General (army group leader)