The difference between 'ADD' and 'DADD'

Question

What is the difference between 'ADD' and 'DADD' MIPS instructions?

I know that 'DADD' stands for Double Word Add but I do not know the difference between 'ADD' and 'DADD'.

Moreover, it appears that both instructions have the same syntax,

e.g.,

ADD R1, R0, R0
DADD R1, R0, R0

Answer 1

ADD is the MIPS32 instruction, DADD is for MIPS64 where registers are 64-bits wide rather than 32.

Both instructions do exactly the same thing, they are used in different MIPS architectures, that's just it.