Ultrasound At 18 Weeks Pregnant...what to Expect!

Hey girls I am now 13 weeks pregnant and I wanted to ask all of you what to expect at my 18 week ultrasound. The only other one I had was when I was 7w5d and that was mostly to confirm my pregnancy-i think but was wondering if they just do pretty much the same thing and also are they usually able to tell what it is? I don't care either way but i'm hoping they'll be able to tell me if babys a boy or a girl.

Thanks!