Is it easier to tell boys or girls on ultrasound?

Frances

I had a gender scan today. I think I’m 13w 6 days but my doctor thinks I’m further and the ultrasound tech is fabulous and has been doing this for over a decade. She was training someone to help her and that person also had a lot of experience. She said they were “pretty sure” but they weren’t 100% so they scheduled me in like a week to check again.

I was thinking boys would probably be more obvious than girls, so their reluctance may indicate a girl. But I was wondering if anyone knew which sex is easier to see on the ultrasound?