What is the difference in XML declarations in XML file with doctype and namespace which resolve bean tag?

We are using Spring 3.0 in one of our projects.

I have an bean definition XML which has declaration.

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://ift.tt/YEoJM4">

and other context file has

<beans xmlns="http://ift.tt/1G3OZos;

What is the difference between these two?

And do both of them try to find the DTD and XSD in classpath?