Evaluate

Basic Examples

The common element 3 is removed from the union of the sets:
[◼]
SymmetricDifference
[{1,2,3},{3,4,5,6}]
In[]:=
{1,2,4,5,6}
Out[]=
Define three lists:
a={1,2,3,4};​​b={2,3,4,5};​​c={3,4,5,6};
In[]:=
Here are their union and intersection:
Union[a,b,c]
In[]:=
{1,2,3,4,5,6}
Out[]=
Intersection[a,b,c]
In[]:=
{3,4}
Out[]=
Here is their symmetric difference:
[◼]
SymmetricDifference
[a,b,c]
In[]:=
{1,2,5,6}
Out[]=

Possible Issues

First define four regions:
{d1,d2,d3,d4}={​​Disk[{1,1},2],​​Disk[{1,-1},2],​​Disk[{-1,-1},2],​​Disk[{-1,1},2]​​};
In[]:=
The function RegionSymmetricDifference is like MultisetSymmetricDifference, not SymmetricDifference:
Region@RegionSymmetricDifference[d1,d2,d3,d4]
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Out[]=
This construction is like SymmetricDifference:
Region@RegionDifference[​​RegionUnion[d1,d2,d3,d4],​​RegionIntersection[d1,d2,d3,d4]​​]
Out[]=