If in case you are not aware, DDR1 and DDR2 are known to help the RAM chip work the best way possible. The DDR1 is considered to be one of the earliest models, so it is not surprising that this is one of the slowest not only when compared to DDR2 but also with the other available types.
DDR means Double Data RAM or Random Access Memory. The power consumption is known to be lesser for the DDR2 as compared to the DDR1. The DDR2 was released in the year 2003, and there are a lot more advanced versions that have been released since then.