The rectus abdomonis, AKA "abs" is the muscle responsible for the "6 pack" appearance.
It begins at the very bottom of the pubis and ends at the bottom of the ribs.
It's 1 muscle.
The whole idea of doing leg raises to target the "lower abs" is nonsense, in fact, the only difference is the focus given to hip flexors as well.
It doesn't matter what exercise you do, if you're using the rectus abdomonis (abs) you will use the whole muscle. It's job is to bring your torso closer to your legs and vice-versa. You cannot specifically target one section of this or any other muscle.
So next time someone tells you they have a program for "lower abs" or have a great exercise for targeting the lower abdominal region, ask them what the name of the lower ab muscle is.
Scientifically, there is no such thing as a "lower ab" muscle, so they will struggle to respond. And if they tell you it's called the rectus abdomonis, you know they're selling a program for something even they can't truly believe exists.
Look at that, I saved you some money!