[VBA] Comparing two columns and pasting the difference into a third column

I'm trying to compare two different columns of products and pasting the different into a third.

If there's a product in column A but isn't in column B. It will show in Column C.

Example:

A | B | C
----------
1 | 2 | 1
2 | 3 | 2
3 | 0 | 0
4 | 5 |


I've just started to pick up VB recently so I'm still a beginner. Any help would be appreciated. Thanks

I do not understand the logic. Number 1 is in column A and not in column B so 1 appears in C - makes sense.
2 appears in column A and in Column B however 2 goes into C - what do you want to appear in C if the number is in Column A and Column B
3 appears in Column A and in Column B and 0 goes into C - should 0 go in to C is the number is not in Column A and Column B?...because this contradicts 2 being in column A and in Column B.
I do not see consistent logic - could you upload a sample workbook with very specific rules about what should appear in C based on Values being in Column A and Column B.

A sample workbook with no private/sensitive data would make things easier.

I get that if the number is in A but not in B then the number in A goes to C. That being said you example above 3 exists in column A and in Column B so should 0 be in C and NOT 5. If the following is correct
A B C
1 2 1
2 3 0
3 0 0
4 5 4

That means if the number is in column A and in column B then 0 (zero) goes into column C - if you could confirm that logic then I can write something for you. If you can as well rather than posting examples in the thread can you please upload sample workbooks (select Go Advanced, Manage Attachments) and you can upload a dummy sample workbook.
If you confirm the logic above please or explain why 5 is in Column C when 3 exists in Column A and Column B

You could do it without VBA using a formula
=IF(ISERROR(MATCH(A1,$B$1:$B$4,0)),A1,0) - Place in C1 and copy down.
Do you particularly want a VBA solution to this?

Your logic still does not make sense
A B C
1 2 1 Existing in column A, but not B - Agree 1 exists in Column A but not B so 1 goes into C
2 3 0 Exists in column B, but not A - 2 exists in Column A and in Column B however you say Exists in Column B but not A.
3 0 5 Exists in column B, but not A - Why is 5 placed here? 3 Exists in Column A and B however you say it exists in Column B but not A
4 5 4 Exists in column A, but not B

I must be missing something. You are checking that a value in A is in column B. I just don't understand your rules. Perhaps someone will understand something I am missing.
I just have no idea why 5 is in row 3?
I am not being mean or aggressive I just do not get your logic rules.

If the number is in A but not in B then the number goes to C. If the number is in B but not in A then it goes to C as well.

That means that there could be 2 outputs into column C.
Could you perhaps upload a slightly larger sample in a workbook - it is obviously clear in your mind but I am just not getting it.

I get your logic now - essentially 2 comparisons are required and an array constructed from the comparisons. If you wanted to just construct a unique list in an array you could use Scripting Dictionary and Keys however your request is different. Try this

Sub compList()
Dim newList, a, x As Long, fnd As Boolean
ReDim newList(x)
With Range("A1")
a = .CurrentRegion
End With
x = 0
For k = 1 To UBound(a)
For t = 1 To UBound(a)
If a(k, 1) = a(t, 2) Then
fnd = True
Exit For
End If
Next
If fnd = False Then
ReDim Preserve newList(x)
newList(x) = a(k, 1)
x = x + 1
End If
fnd = False
Next
For k = 1 To UBound(a)
For t = 1 To UBound(a)
If a(k, 2) = a(t, 1) Then
fnd = True
Exit For
End If
Next
If fnd = False Then
ReDim Preserve newList(x)
newList(x) = a(k, 2)
x = x + 1
End If
fnd = False
Next
For k = LBound(newList) To UBound(newList)
Range("C" & k + 1) = newList(k)
Next
End Sub

See attachment for example.

Here is a slightly more elegant solution

Sub recipList()
Dim arr1, arr2, recipArr, x, i As Long
ReDim recipArr(i)
arr1 = Range("A1:A" & Cells(Rows.Count, "A").End(xlUp).Row).Value
arr2 = Range("B1:B" & Cells(Rows.Count, "B").End(xlUp).Row).Value
For Each x In arr1
    If IsError(Application.Match(x, arr2, 0)) Then
        ReDim Preserve recipArr(i)
        recipArr(i) = x
        i = i + 1
    End If
Next
For Each x In arr2
If IsError(Application.Match(x, arr1, 0)) Then
        ReDim Preserve recipArr(i)
        recipArr(i) = x
        i = i + 1
    End If
Next
For k = LBound(recipArr) To UBound(recipArr)
Range("C" & k + 1) = recipArr(k)
Next
End Sub

@Winon
A good idea - the OP's example was a semi sorted list so this is a nice addition.
Thanks