Günaydın

What´s the difference between :"okuduğunu and okumasını "?

My amateur guess:

okuduğunu = "that you read". See the use of ´dik´: http://www.turkishclass.com/turkish_lesson_299 

okumasını = "your reading" whereby okuma/reading is a noun.

See also "Turning Verbs into Nouns- Difference between -DIK and -MA" http://www.turkishclass.com/forumTitle_54399

Maybe examples help you to understand. 

He asked me what i´m reading.

Bana ne okuduğumu sordu.

He adviced to her to read that book.

Ona bu kitabı okumasını tavsiye etti.

Thank you for help ,a little complicated to understand.