This photo is symmetrical because in the center of the photo there is a silhouette of a church tower, then either side there are trees of the same height and size roughly the same distance away from the church. The clouds above the church are also the same size, shape and width. But whereas the the silhouettes are vertically symmetrical, the clouds above the silhouettes are horizontally symmetrical because the clouds look very similar in most ways.
This photo isn't a completely symmetrical photo because even though the girls are stood in exactly the same position and are the same width away from the edge of the photo they are not wearing the same clothing, don't have the same hairstyle and are not the same height and weight.
This photo is symmetrical because the bars of the fence are the same and there are the same amount of bars on either side of the photo. Also on the edges of the picture there are two parts of the pointed ends of the fence on either side of the photo. The sun is directly in the center of the picture, therefore the colours of the sky are distributed evenly and symmetrically as well.
