Afraid to do or afraid of doing?

A Afraid

David is afraid to climb the ladder. (He doesn't want to climb the ladder because he is afraid.)

David is afraid of falling. (He is afraid because he might fall.)

Here are some more examples.

I was afraid to say anything in front of all those people.

Claire was afraid to wander too far from the hotel.

I was afraid of sounding foolish, you see.

She was afraid of getting lost.

Compare these examples.

Zedco are anxious to increase their sales. (They want to increase their sales.)

Mark was anxious about presenting his report. (He was worried because he had to present his report.)

I'm ashamed to tell you what I scored in the test. (I don't want to tell you because I'm ashamed.)

I'm ashamed of getting such a low score. (I'm ashamed because I got such a low score.)

I'd be interested to meet Laura. (I want to meet her.)

Laura is interested in painting. (It is an interest/a hobby of hers.)

I was interested to hear Mike's story. (I found his story interesting.)

To apologize for something we are doing, we use a to+infinitive.

I'm sorry to tell you this, but your test score is rather low.

I'm sorry to ring so late, but it's important.

To express regret, we also use a to+infinitive.

I was sorry to hear that Mike's uncle had died.

To apologize for something we did, we can use about + -ing form.

I'm sorry about making all that noise last night. (OR I'm sorry I made all that noise last night.)