"seen" VS "shown"

What is the difference between 'can be seen' and 'can be shown'?
  • can be seen-boleh dilihat
  • can be shown-boleh ditunjukkan
Therefore,
  1. The theme 'love is important in a family' can be seen throughout the novel. (correct)
  2. The theme 'love is important in a family' can be shown throughout the novel. (wrong)