It's not the same end result. There are huge psychological issues that can come up with being the genetic mother to your child but having someone else carry them for you. Then you also have to figure out how (if?) the surrogate is involved in the child's life at all, how you explain to the child that someone else birthed them, etc. If you ever find yourself favoring one child over another, you'll always wonder if it's because it's not "your" baby.

Basically, it's not as simple as just handing off an embryo to another person and 9 months later acting like nothing happened. There are huge ramifications to a decision like this that don't come with being the birth mother.