can someone please clear this up?

You guys are about to think I'm really dumb. I'm not. I swear. I'm just a FTM. So I read that once a baby starts drinking from a bottle, throw it away within an hour. Fine, I get that. But then I read you can pour and mix bottles and keep them refrigerated for 24 hours. So, what's the difference between pouring the bottle and having baby drink it and pouring the bottle and storing it? Hope this makes sense.