What is the difference between Have sth done and Get sth done?

i've already known that get is a little more informal than have in this case. Tell me the other ones.
- Firstly, i've read in oxford pocket grammar that "have sth done" is used to infer to an umnpleasant experience, but in grammar book (destination C1 and C2 - grammar and vocabulary by Macmillan) they are both the same (i think so).
In the grammar book: "Having/getting our car stolen was so annoying because it meant i had to take the tube to work"
In Oxford pocket grammar: "My sister has had some money stolen"
- Secondly, oxford pocket grammar shows that "we use it (have/get sth done) to talk about professional services to acustomer.
" Where did you have/get your hair cut?"
And in the grammar book, "Have you thought about having your hair cut as short as mine?" Why does just "have" stand here? Why not "get"?
I think that the things i've mentioned above are the differences between "Have sth done" and "Get sth done" but they really get me confused. Please give some explanations to me abou these things.
Tell me the other differences too.
Thanks for reading such long questions like these.
Best regards.