About the Order of Groups Is there any theorem that states the all the finite groups of order n are the same? or some sort of theorem that refers to the order of two finite groups?
If anyone can post a reference to this topic will be great...
10x in advance

Not all groups of order n are the same.
$\mathbb{Z}_6$ and $S_3$ are both of order 6. However $S_3$ has 3 subgroups of order 2, where $\mathbb{Z}_6$ has only one subgroup of order 2. 
Therefore they cannot be isomorphic.
