Flotation suits

I mainly shore fish - thinking of getting a flotation suit. But what is the different purpose of a one-piece versus two-piece?

i have had both the two piece is better for fishing as you can wear the top with waders if its cold and you are getting surf up your legs ,the one piece is ok for rock fishing and steep beaches both keep you just as warm,the one piece would be slightly better for survival should you fall in not that any of us intend to

guys can pee easiers in both lol.