Find a complete description of the differences here.
The are different in:
The complementary and antiparallel double helix
Single stranded polynucleotides: mRNA, rRNA and tRNA.
The "eight plus one" DNA compaction system: from 5 cm to 5 um
Synthesis of DNA from two DNA template strands: leading and lagging
Synthesis of mRNA and gene expression: using the info in DNA
Synthesis of proteins: reading the code to make molecular machines