Question

How can a DDR1 ram be identified from a DDR2 ram module physically?

Answer 1

You can usually identify the type of RAM it is by the speed rating on the label, if it doesn't outright say the DDR type.

DDR: PC-1600 to PC-3200

DDR2: PC2-3200 to PC2-8500

DDR3: PC3-6400 to PC3-17000

If there is no label, you will have to google the model number printed on all of the chips.