i'm afraid to和i'm afraid of doing 之间的区别是什么?

e afraid doing/to do
be afraid to do 不敢,胆怯去做某事,是主观上的原因不去做,意为"怕"；
be afraid of doing 担心出现doing的状况、结果.doing 是客观上造成的,意为"生怕,恐怕".
She was afraid to step further in grass because she was afraid of being bitten by a snake.
她生怕被蛇咬着,而不敢在草丛中再走一步.
She was afraid to wake her husband.
她不敢去叫醒她丈夫.
She was afraid of waking her husband.
她生怕吵醒她丈夫.

正如你所说，be afraid to do; be afraid of doing。
本质上是无区别的，后者可能多了一些担忧的意思。而前者只是害怕。

i'm afraid to do是"不敢做....",i'm afraid of doing 是"...怕后果".