DDR and DDR2 Memory

Can a motherboard that accepts DDR2 memory accept DDR memory? i know it probably can't, but I wasn't 100% certain.....

There are physical differences between DDR2 and DDR memory. DDR2 has a 240-pin count as opposed to the 184-pin DDR. DDR2 only uses BGA (Ball Grid Array) memory chips and only needs 1.8v for voltage, as opposed to the TSOP and 2.5v standard of DDR.

(from here)