Research has shown that it adds nothing to the safety of the birth and has the potential for long-term problems, so I don't understand why they are still done so frequently. Maybe that is one of the differences you asked about. Another is position for laboring and giving birth. I will catch a baby in whatever position mom is most comfortable at the time. I have preferences based on reducing tears and other problems, but usually I can be very flexible about this.
Labor is almost always more efficient if the woman is up and about.
There are a million anxieties in pregnancy. Some are about important things and some are not, some are just what happens because of hormones. I've have extreme panic the past 2 weeks and am only 6 months. Breathing techniques work well especially when they are familiar to you, but they fall short if you experience full-blown panic. I just don't want to put any stress on my baby.