Qual é a diferença entre I wrote to him e I wrote for him ?Podes indicar apenas respostas exemplo.

"to" is always you wrote it for that recipient
"for" sometimes has that same meaning, but sometimes means something else


"I wrote a letter to Bob" = I wrote a letter (and sent it) to Bob
"I wrote a letter for Bob" = I wrote a letter (and sent it) to Bob [same thing]

"I wrote a book for my son Jeremy" could mean:
1) I wrote a book for Jeremy and sent it to him, OR
2) I wrote a book dedicated to Jeremy

"I once wrote to President Obama" = I wrote something (probably a letter) and sent it to President Obama

"I once wrote for President Obama" probably means I wrote a speech for President Obama and he gave the speech