Difference between a 2500 and a 2600 (cisco) routers

What is the basic differences between a cisco 2500 and a cisco 2600 router?
Thinking from a point of view that if I was to buy one of these for practicing all the CCNA stuff.

The main difference between the two series are the modules.





The 2500 series does not have modules.





The 2600 series does have modules.



Aside from that there may be some IOS differences but nothing I care to go into. The big deal between the two is the 2600 can be equipped with new modules and use the connector configuration based on the network designers needs.