For mainly portrait photography, should I purchase the Canon 50D or the 5D Mark II? Experienced users please!?

Hi! I'm looking to find out the major differences between the Canon 50D and the 5D Mark II? I am a first time D-SLR buyer, and have narrowed my options down to these 2. I mainly enjoy taking photographs of people, primarily babies. Right now, I only take pictures of family as a serious hobby, but I'd like... show more Hi! I'm looking to find out the major differences between the Canon 50D and the 5D Mark II? I am a first time D-SLR buyer, and have narrowed my options down to these 2. I mainly enjoy taking photographs of people, primarily babies. Right now, I only take pictures of family as a serious hobby, but I'd like to have the right camera to grow with me in the case I want to take the next step. What are the major differences between the 2 cameras? Which is a better camera for portrait photography? (Mainly in non-studio, indoor/and outdoor settings). Which is the best lens to purchase for each of these for portrait photography? Please answer if you get a chance! Thank you so much for your help!
Update: David M - You made SUCH A GOOD POINT about the flash! I am SO glad I read that, because I had no idea! I have no idea how to use a shoe mount flash, so you really helped make my decision. That being said... By "pop up flash" do you mean the flash that just flips up and down when you turn on the camera?... show more David M - You made SUCH A GOOD POINT about the flash! I am SO glad I read that, because I had no idea! I have no idea how to use a shoe mount flash, so you really helped make my decision. That being said... By "pop up flash" do you mean the flash that just flips up and down when you turn on the camera? (For example.. My husband has the rebel XS camera.... is the flash similar to this in the way it flips up and down automatically?)
If anyone has any comparisons between what I can expect the same/or differently between a 50D and the Rebel XS, please feel free to share. (when it comes to picture quality... size of camera, etc)
Lastly, Casperskitty - you said I have to start thinking about flash and lighting... What did you mean by this? Do I have to buy additional parts that I do not know about? You had the Rebel (like my husband's), do you have any comparisons to a 50D that you know of?
THANK YOU EVERYONE! You've seriously helped me more than anyone else online! Thank you!!!
Update 2: Thank you so much for your very detailed and thoughtful responses!!! You all gave great advice, and I decided to go with the 50D, per your advice So that being said, if you're still reading this post, please help me with follow up questions! I'll warn you all in advance - I have not been professionally... show more Thank you so much for your very detailed and thoughtful responses!!! You all gave great advice, and I decided to go with the 50D, per your advice So that being said, if you're still reading this post, please help me with follow up questions!
I'll warn you all in advance - I have not been professionally trained so I'm not familiar with correct terminology for things
MixedMojo - You spoke of the "wide angle" of the 5D compared to 50D. Is this very important if i'm just taking a picture of say 1 person, or in particular, 1 baby? having chosen the 50D, do you have a different reccomendation for me as far as which lens is the best for me to buy? Price is no object, and again, I mainly need this camera for taking picture of 1 person or a very small group (3 or 4) people at a time. Never pictures of landscape, or large groups of people. Mainly, I take pictures of babies. Also, I do not use studio lighting. It's mainly indoors in crappy, normal lighting... And/or very occasionally outside
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