I don't think you can begin to compare Aberfan and Dunblane.
One was entirely preventable and cost the lives of 116 children and 28 adults, the other was an horrendous individual who took the life of 16 children and one adult, then killed himself.
Perhaps because I was young when Aberfan happened it has stayed with me forever. Seeing on TV the men digging in the mud with their bare hands, the silence when everything stopped at a whistle because somebody thought they heard something will never leave me. Asking "mum, have they found someone?" and seeing the tears rolling down her cheeks.
Dunblane was truly awful and every child lost was a tragedy as well as their teacher, but that was one deranged individual and thank goodness the tightened laws and safety rules for schools have ensured there's never been a repeat.
It isn't just 'big anniversaries' for the families concerned, every day is a day without their loved ones, it must hurt so much.