Going to do 3D or 4D fetal photos!

Me and Fiancé are excited to go get pictures of our baby. We will be able to see facial features more clearly and everything ❤️🙂 We are very excited, also will be doing all the DNA BLOOD tests and stuff so we can find out the gender of our lil one a lil earlier. Oh question which is better 3D or 4D? What's the difference?