This video explains difference in layout between DDR3 (fly-by topology) and DDR2 (T-branch topology).
This video explains how to do DDR2 / DDR3 length matching in Altium Designer.
Download PCB brd files and see examples of DDR, DDR2 and DDR3 layouts. Pictures show difference between DDR2 and DDR3 address routing.
Video: This video has been taken when I was doing DDR2 layout using Altium Designer.
I have used this spreadsheet to calculate DDR2 length for one of projects. I hope it helps to other people.