The difference between ∈ and ⊂ I had a task where I had to figure if the argument was true or not.
$A=\{ n ∈ ℤ \mid n^2 < 5 \}, \quad  B=\{ 7, 8, \{2\}, \{2, 7, 8\}, \{\{7\}\} \}$
The first one was $\{-1, 2\} ∈ A$ and the answer to this was not true
 since the set is not an integer.
The second one was $\{-1, 2\} ⊂ A$ and the answer to this was true since
 -1 and 2 are elements of $A$.
I just can't seem to understand the difference between ∈ and ⊂ in this task and why the first argument was not true. Also it confuses me that the answer to the first one was that not true because the set is not an integer but aren't -1 and 2 integers?
There is other parts of this task that also add more confusion:

{2, 7, 8} ∈ B Answer: True since {2, 7, 8} is an element of set B
{2, 7, 8} ⊂ B Answer: Not true, for example 2 is not an element in set
  B


$\in$ stands for "belongs to".For eg. an element may belong to a set.
$\subset$ is the symbol for subset .For eg. one set can be a subset of another set if all elements of that set is included in the later set.
You must be careful on what you are applying $\in$ or $\subset$.
